anchor.diff:    final String actionText;
   
     final Function(
  -    DevToolsJsonFile firstImportedFile,
  -    DevToolsJsonFile secondImportedFile,
  +    DevToolsJsonFile? firstImportedFile,
  +    DevToolsJsonFile? secondImportedFile,
       void Function(String error) onError,
     ) onAction;
   
  
positive.code: // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // @dart=2.9
  
  import 'dart:convert';
  
  
negative.code:             importedFile?.path ?? 'No File Selected',
              overflow: TextOverflow.ellipsis,
              style: TextStyle(
                color: Theme.of(context).textTheme.headline1!.color,
              ),
              textAlign: TextAlign.left,
            ),
  