Add point about initializing localization objects on 'Internationalizing Flutter apps' page

[akiross]

Page URL

https://docs.flutter.dev/accessibility-and-localization/internationalization

Page source

https://github.com/flutter/website/tree/main/src/docs/development/accessibility-and-localization/internationalization.md

Describe the problem

In the page, step 8, it is mentioned that

8. Use AppLocalizations anywhere in your app. Here, the translated message is used in a Text widget.

but I believe this is a bit misleading, because "anywhere" led me to naively think that this code was valid:

import 'package:flutter_gen/gen_l10n/app_localizations.dart';

void main() => runApp(MyWidget());

class MyWidget extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
        return MaterialApp(
            localizationsDelegates: AppLocalizations.localizationsDelegates,
            supportedLocales: AppLocalizations.supportedLocales,
            home: Text(AppLocalizations.of(context)!.helloWorld));
    }

But it does not, because the localization objects are not yet initialized when the AppLocalizations.of(context)!.helloWorld is evaluated, so things crash with a null exception. It's simple to understand that AppLocalizations.of(context) is null in this instance, but it's not obvious that it is because it is uninitialized.

Expected fix

I believe the documentation could be a little more clear and contextually mention (in point 7 or 8) that the material app has to actually be started to initialize the AppLocalizations and that using AppLocalizations.of(context)!.helloWorld won't work before that.

In retrospective the error is clear, but a minor fix could help avoiding this problem at all.

Additional context

No response

[sfshaza2]

That is an excellent point, @akiross! I have updated the text.