anchor.diff:            ErrorHint(
               'Instead of performing asynchronous work inside a call to setState(), first '
               'execute the work (without updating the widget state), and then synchronously '
  -           'update the state inside a call to setState().',
  +            'update the state inside a call to setState().',
             ),
           ]);
         }
  
positive.code:         // TODO(a14n): remove this check to have a lot more const widget
          if (children[index] == null) {
            throw FlutterError(
                "$runtimeType's children must not contain any null values, "
                    'but a null value was found at index $index',
            );
          }
        }
  
negative.code:               error = FlutterError.fromParts(<DiagnosticsNode>[
                  ErrorSummary('Multiple widgets used the same GlobalKey.'),
                  ErrorDescription(
                    'The key $key was used by multiple widgets. The parents of those widgets were:\n'
                    '- ${older.toString()}\n'
                    '- ${newer.toString()}\n'
                    'A GlobalKey can only be specified on one widget at a time in the widget tree.',
                  ),
                ]);
              } else {
                error = FlutterError.fromParts(<DiagnosticsNode>[
                  ErrorSummary('Multiple widgets used the same GlobalKey.'),
                  ErrorDescription(
                    'The key $key was used by multiple widgets. The parents of those widgets were '
                    'different widgets that both had the following description:\n'
                    '  ${parent.toString()}\n'
                    'A GlobalKey can only be specified on one widget at a time in the widget tree.',
                  ),
                ]);
              }
  