Fix exception when using "Select Widget Mode" of the Flutter Inspector:

```
Exception has occurred.
FlutterError (Tried to modify a provider while the widget tree was building.
If you are encountering this error, chances are you tried to modify a provider
in a widget life-cycle, such as but not limited to:
- build
- initState
- dispose
- didUpdateWidget
- didChangeDependencies

Modifying a provider inside those life-cycles is not allowed, as it could
lead to an inconsistent UI state. For example, two widgets could listen to the
same provider, but incorrectly receive different states.

To fix this problem, you have one of two solutions:
- (preferred) Move the logic for modifying your provider outside of a widget
  life-cycle. For example, maybe you could update your provider inside a button's
  onPressed instead.

- Delay your modification, such as by encapsulating the modification
  in a `Future(() {...})`.
  This will perform your update after the widget tree is done building.)
```

And adjust the GitHub button size to match the now larger Discord button.

If the last episode of an Anime has ended, exit fullscreen mode.

When leaving the Code Editor of certain Extensions, this Exception would throw:
```
[ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: Runtime Error: Undefined variable: source (Original error: Undefined property 'source' on Madara.)
#0      InterpreterVisitor.visitSimpleIdentifier (package:d4rt/src/interpreter_visitor.dart:393:7)
interpreter_visitor.dart:393
#1      SimpleIdentifierImpl.accept (package:analyzer/src/dart/ast/ast.dart:16123:50)
ast.dart:16123
#2      InterpreterVisitor.visitPostfixExpression (package:d4rt/src/interpreter_visitor.dart:3930:41)
interpreter_visitor.dart:3930
#3      PostfixExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:14311:50)
ast.dart:14311
#4      InterpreterVisitor._evaluateArguments (package:d4rt/src/interpreter_visitor.dart:5569:23)
interpreter_visitor.dart:5569
#5      InterpreterVisitor.visitMethodInvocation (package:d4rt/src/interpreter_visitor.dart:2178:13)
interpreter_visitor.dart:2178
kodjodevf#6      MethodInvocationImpl.accept (package:analyzer/src/dart/ast/ast.dart:12246:50)
ast.dart:12246
kodjodevf#7      InterpretedClass.createAndInitializeInstance (package:d4rt/src/runtime_types.dart:232:53)
runtime_types.dart:232
kodjodevf#8      InterpretedClass.call (package:d4rt/src/runtime_types.dart:299:22)
runtime_types.dart:299
kodjodevf#9      InterpreterVisitor.visitMethodInvocation (package:d4rt/src/interpreter_visitor.dart:2161:28)
interpreter_visitor.dart:2161
kodjodevf#10     MethodInvocationImpl.accept (package:analyzer/src/dart/ast/ast.dart:12246:50)
ast.dart:12246
kodjodevf#11     InterpreterVisitor.visitVariableDeclarationList (package:d4rt/src/interpreter_visitor.dart:3026:42)
interpreter_visitor.dart:3026
kodjodevf#12     VariableDeclarationListImpl.accept (package:analyzer/src/dart/ast/ast.dart:18695:15)
ast.dart:18695
kodjodevf#13     InterpreterVisitor.visitVariableDeclarationStatement (package:d4rt/src/interpreter_visitor.dart:135:27)
interpreter_visitor.dart:135
kodjodevf#14     VariableDeclarationStatementImpl.accept (package:analyzer/src/dart/ast/ast.dart:18753:15)
ast.dart:18753
kodjodevf#15     InterpreterVisitor.executeBlock (package:d4rt/src/interpreter_visitor.dart:66:33)
interpreter_visitor.dart:66
kodjodevf#16     InterpretedFunction.call (package:d4rt/src/callable.dart:589:36)
callable.dart:589
kodjodevf#17     D4rt.execute (package:d4rt/src/d4rt_base.dart:220:43)
d4rt_base.dart:220
kodjodevf#18     DartExtensionService._executeLib (package:mangayomi/eval/dart/service.dart:24:17)
service.dart:24
kodjodevf#19     DartExtensionService.getSourcePreferences (package:mangayomi/eval/dart/service.dart:179:25)
service.dart:179
kodjodevf#20     getSourcePreference (package:mangayomi/services/get_source_preference.dart:6:38)
get_source_preference.dart:6
kodjodevf#21     _ExtensionDetailState.build.<anonymous closure>.<anonymous closure> (package:mangayomi/modules/browse/extension/extension_detail.dart:173:44)
extension_detail.dart:173
kodjodevf#22     State.setState (package:flutter/src/widgets/framework.dart:1199:30)
framework.dart:1199
kodjodevf#23     _ExtensionDetailState.build.<anonymous closure> (package:mangayomi/modules/browse/extension/extension_detail.dart:171:23)
extension_detail.dart:171
<asynchronous suspension>
```