Correct missing return statements in nullably-typed functions (#95428)

examples/api/lib/widgets/actions/action.action_overridable.0.dart

@@ -43,6 +43,7 @@ class DigitInputState extends State<DigitInput> {
     onInvoke: (DeleteCharacterIntent intent) {
       // For simplicity we delete everything in the section.
       widget.controller.clear();
+      return null;
     },
   );
 
@@ -84,7 +85,7 @@ class _DeleteDigit extends Action<DeleteCharacterIntent> {
 
   final _SimpleUSPhoneNumberEntryState state;
   @override
-  Object? invoke(DeleteCharacterIntent intent) {
+  void invoke(DeleteCharacterIntent intent) {
     assert(callingAction != null);
     callingAction?.invoke(intent);
 

packages/flutter_tools/lib/src/commands/ide_config.dart

@@ -273,4 +273,6 @@ String? _validateFlutterDir(String dirPath, { String? flutterRoot }) {
     case FileSystemEntityType.notFound:
       return null;
   }
+  // In the case of any other [FileSystemEntityType]s, like the deprecated ones, return null.
+  return null;
 }