Flutter FutureBuilder gives error The method '[]' can't be unconditionally invoked because the receiver can be 'null'

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Trying to do a shpping cart project in flutter error is : The method '+' can't be unconditionally invoked because the receiver can be 'null'

The method '+' can't be unconditionally invoked because the receiver can be 'null'. Flutter Dart

The function can't be unconditionally invoked because it can be 'null'. The '!' will have no effect because the receiver can't be null

Flutter exception: The method 'forEach' was called on null. Receiver: null Tried calling: forEach(Closure: (CarModel) => Null)

Unity C# Class new method gives an error 'Class' doesn't contain a definition for 'name'

Error 'The argument type 'bool Function(EmployeeDetails)' can't be assigned to the parameter type 'bool Function(SalesDetails)?' in flutter

Can't pip install to target (distutils.errors.DistutilsOptionError: can't combine user with prefix, exec_prefix/home, or install_(plat)base)

Why can't I invoke a static method inside the class body?

Ionic jspdf error cannot Module not found: Error: Can't resolve 'jspdf'

Webpack 4 : ERROR in Entry module not found: Error: Can't resolve './src'

The method 'toDouble' was called on null. Receiver: null Tried calling: toDouble()

Combining Laravel + Vue.js I got Error: "Module not found: Error: Can't resolve './vue/app'"

MySql Error: Can't update table in stored function/trigger because it is already used by statement which invoked this stored function/trigger

Flutter 'File' can't be assigned to 'XFile'

Rails 4 - Can't render 404 in production with dynamic error page (Error during failsafe response: Missing template errors/show)

The method 'of' isn't defined for the type 'ThemeProvider'. in Flutter

Error: The method 'unawaited' isn't defined for the class 'RateMyApp'

Django 4 Pycharm debugger error: can't find '__main__' module in ''

The getter 'documents' isn't defined for the type 'QuerySnapshot' error in Flutter Firebase

Anuj TBE · Answer 1

In this case you can just use ! to solve this since you're already checking snapshot.hasData

return ListTile(
       title: Text(snapshot.data![i].phoneNumber),
);

But in general you have to store the snapshot.data in a local variable and check if it's null or not. Dart can only promote local variables, not getters. So even if you check snapshot.hasData or snapshot.data != null is not enough and dart can't promote the getters. The following is from documentation:

Flow-based type promotion does not apply to fields because the static analysis cannot prove that the field’s value doesn’t change between the point that you check for null and the point that you use it. (Consider that in pathological cases, the field itself could be overridden by a getter in a subclass that returns null the second time it is called.)

body: FutureBuilder<List<RecordModel>>(
        future: DatabaseProvider.instance.records(),
        builder: (context, snapshot) {
          final data = snapshot.data;
          if (data != null) {

            return ListView.builder(
                itemCount: snapshot.data?.length,
                itemBuilder: (itemBuilder, i) {
                  return ListTile(
                    title: Text(data[i].phoneNumber),
                  );
                });
          } else if (snapshot.hasError) {
            return const Center(
              child: Text('Oops...'),
            );
          } else {
            return const Center(
              child: CircularProgressIndicator(),
            );
          }
        },
      ),

ProgrammerAnswered 1 years ago · Answer 2

I/flutter (14827): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (14827): The following assertion was thrown building FutureBuilder<bool>(dirty, state:
I/flutter (14827): _FutureBuilderState<bool>#6904b):
I/flutter (14827): Failed assertion: boolean expression must not be null
I/flutter (14827): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (14827): more information in this error message to help you determine and fix the underlying cause.
I/flutter (14827): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (14827):   https://github.com/flutter/flutter/issues/new
I/flutter (14827): When the exception was thrown, this was the stack:
I/flutter (14827): #0      MyApp.build.<anonymous closure> (file:///Users/user/Documents/sellquick_app/lib/main.dart)
I/flutter (14827): #1      _FutureBuilderState.build (package:flutter/src/widgets/async.dart)
I/flutter (14827): #2      StatefulElement.build (package:flutter/src/widgets/framework.dart:3743:27)
I/flutter (14827): #3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3655:15)
I/flutter (14827): #4      Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #5      ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #6      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #7      ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #8      Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #9      Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #10     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #11     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #12     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #13     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #14     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #15     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #16     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #17     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #18     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #19     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #20     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #21     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #22     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #23     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #24     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #25     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #26     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #27     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #28     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #29     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #30     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #31     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #32     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #33     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #34     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #35     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #36     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #37     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #38     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #39     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #40     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #41     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #42     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #43     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #44     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #45     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #46     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #47     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #48     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #49     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #50     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #51     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #52     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #53     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #54     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #55     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #56     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #57     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #58     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #59     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #60     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #61     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #62     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #63     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #64     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #65     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #66     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #67     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #68     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #69     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #70     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #71     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #72     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #73     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #74     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #75     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #76     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #77     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #78     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #79     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #80     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #81     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #82     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #83     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #84     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #85     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #86     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #87     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #88     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #89     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #90     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #91     Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #92     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #93     Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #94     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #95     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #96     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #97     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #98     MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4772:32)
I/flutter (14827): #99     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #100    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #101    _TheatreElement.mount (package:flutter/src/widgets/overlay.dart:493:16)
I/flutter (14827): #102    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #103    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #104    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #105    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #106    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #107    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #108    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #109    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #110    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #111    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #112    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #113    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #114    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #115    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #116    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #117    SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #118    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #119    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #120    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #121    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #122    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #123    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #124    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #125    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #126    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #127    SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #128    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #129    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #130    SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #131    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #132    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #133    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #134    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #135    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #136    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #137    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #138    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #139    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #140    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #141    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #142    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #143    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #144    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #145    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #146    SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #147    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #148    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #149    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #150    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #151    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #152    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #153    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #154    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #155    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #156    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #157    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #158    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #159    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #160    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #161    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #162    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #163    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #164    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #165    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #166    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #167    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #168    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #169    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #170    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #171    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #172    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #173    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #174    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #175    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #176    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #177    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #178    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #179    SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4667:14)
I/flutter (14827): #180    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #181    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #182    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #183    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #184    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #185    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #186    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #187    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #188    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #189    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #190    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #191    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #192    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #193    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #194    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #195    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #196    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #197    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #198    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #199    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #200    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #201    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #202    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #203    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #204    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #205    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #206    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #207    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #208    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #209    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #210    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #211    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #212    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #213    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #214    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #215    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #216    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #217    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #218    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #219    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #220    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #221    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #222    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #223    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #224    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #225    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #226    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #227    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #228    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #229    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #230    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #231    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #232    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #233    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #234    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #235    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #236    StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3782:11)
I/flutter (14827): #237    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #238    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #239    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #240    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3666:16)
I/flutter (14827): #241    Element.rebuild (package:flutter/src/widgets/framework.dart:3508:5)
I/flutter (14827): #242    ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3635:5)
I/flutter (14827): #243    ComponentElement.mount (package:flutter/src/widgets/framework.dart:3630:5)
I/flutter (14827): #244    Element.inflateWidget (package:flutter/src/widgets/framework.dart:2920:14)
I/flutter (14827): #245    Element.updateChild (package:flutter/src/widgets/framework.dart:2723:12)
I/flutter (14827): #246    RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:857:16)
I/flutter (14827): #247    RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:828:5)
I/flutter (14827): #248    RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:774:17)
I/flutter (14827): #249    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2235:19)
I/flutter (14827): #250    RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:773:13)
I/flutter (14827): #251    _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&RendererBinding&WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:662:7)
I/flutter (14827): #252    runApp (package:flutter/src/widgets/binding.dart:704:7)
I/flutter (14827): #253    main (file:///Users/user/Documents/sellquick_app/lib/main.dart:13:16)
I/flutter (14827): #254    _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:279:19)
I/flutter (14827): #255    _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)
I/flutter (14827): ════════════════════════════════════════════════════════════════════════════════════════════════════

@zoechi here's my code snippet. Something wrong I didn't detect?

return new MaterialApp(
    ...
      home: new FutureBuilder<bool>(
          future: sessionManager.isLoggedIn(), //Async method (this returns false by default if null)
          builder: (BuildContext context, AsyncSnapshot<bool> isLoggedIn) {
            return isLoggedIn.data ? new MainPageWidget() : new IntroWidget();
          }),
...

ProgrammerAnswered 1 years ago · Answer 3

flutter doctor:

[✓] Flutter (Channel stable, v1.17.2, on Mac OS X 10.15.4 19E287, locale ko-KR)
 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
[✓] Xcode - develop for iOS and macOS (Xcode 11.4.1)
[✓] Android Studio (version 4.0)
[!] IntelliJ IDEA Community Edition (version 2019.2.3)
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[!] VS Code (version 1.45.1)
    ✗ Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter
[!] Connected device

flutter doctor -v

[✓] Flutter (Channel dev, 1.19.0-1.0.pre, on Mac OS X 10.15.5 19F96, locale en-GB)
    • Flutter version 1.19.0-1.0.pre at /Users/tahatesser/Code/flutter_dev
    • Framework revision 456d80b9dd (3 weeks ago), 2020-05-11 11:45:03 -0400
    • Engine revision d96f962ca2
    • Dart version 2.9.0 (build 2.9.0-7.0.dev 092ed38a87)

 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/tahatesser/Code/sdk
    • Platform android-29, build-tools 29.0.3
    • ANDROID_HOME = /Users/tahatesser/Code/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.5)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.5, Build version 11E608c
    • CocoaPods version 1.9.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.0)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 45.1.2
    • Dart plugin version 193.7361
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] VS Code (version 1.45.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.11.0

[✓] Connected device (3 available)
    • macOS      • macOS      • darwin-x64     • Mac OS X 10.15.5 19F96
    • Web Server • web-server • web-javascript • Flutter Tools
    • Chrome     • chrome     • web-javascript • Google Chrome 83.0.4103.61

• No issues found!

Have this issue on master channel

Flutter 1.19.0-2.0.pre.214 • channel master • git@github.com:flutter/flutter.git
Framework • revision 1d395c5e18 (il y a 23 heures) • 2020-05-31 07:41:50 -0700
Engine • revision 923687f0e7
Tools • Dart 2.9.0 (build 2.9.0-13.0.dev 6489a0c68d)

Don't have the issue on beta channel

[✓] Flutter (Channel beta, 1.18.0-11.1.pre, on Linux, locale fr_FR.UTF-8)
    • Flutter version 1.18.0-11.1.pre at /home/rbarbe/programes/flutter
    • Framework revision 2738a1148b (il y a 3 semaines), 2020-05-13 15:24:36 -0700
    • Engine revision ef9215ceb2
    • Dart version 2.9.0 (build 2.9.0-8.2.beta)

Appears to be broken in 1.26.0-1.0.pre. I am forced to use the dev channel because Android Studio 4.1 is not compatible with the current stable channel due to this issue: #67986

[✓] Flutter (Channel dev, 1.26.0-1.0.pre, on Mac OS X 10.15.7 19H2 darwin-x64,
    locale en-US)
    • Flutter version 1.26.0-1.0.pre at /Users/dallen/dev/flutter
    • Framework revision 63062a6443 (2 weeks ago), 2020-12-13 23:19:13 +0800
    • Engine revision 4797b06652
    • Dart version 2.12.0 (build 2.12.0-141.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    • Android SDK at /Users/dallen/Library/Android/sdk
    • Platform android-30, build-tools 29.0.2
    • ANDROID_HOME = /Users/dallen/Library/Android/sdk
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.7)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.7, Build version 11E801a
    • CocoaPods version 1.10.0

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)

[✓] IntelliJ IDEA Ultimate Edition (version 2020.2.3)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 51.0.3
    • Dart plugin version 202.8070

[✓] Connected device (1 available)
    • iPhone SE (2nd generation) (mobile) • EE8071D5-EEB7-4079-9A97-27C225371E41
      • ios • com.apple.CoreSimulator.SimRuntime.iOS-13-7 (simulator)

• No issues found!

Flutter FutureBuilder gives error The method '[]' can't be unconditionally invoked because the receiver can be 'null'

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Flutter FutureBuilder gives error The method '[]' can't be unconditionally invoked because the receiver can be 'null'

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