Couldn't able to generate mocks for Main Router

[GayathriDeviSrinivasan]

@AutoRouterConfig(
  replaceInRouteName: 'Page,Route,Screen',
)


``````dart
class MainRouter extends RootStackRouter {

}

class TestRouter extends Mock implements MainRouter, RootStackRouter {}

MockSpec<TestRouter>(as: Symbol('MockTestRouter'), onMissingStub: OnMissingStub.returnDefault),

Error:

 [SEVERE] mockito:mockBuilder on test/test_utils/test_mocks.dart:

Bad state: No element
dart:core                                               List.first
package:source_gen/src/constants/revive.dart 104:21     reviveInstance
package:source_gen/src/constants/reader.dart 278:25     _DartObjectConstant.revive
package:mockito/src/builder.dart 407:34                 _TypeVisitor._addTypesFromConstant
package:mockito/src/builder.dart 303:7                  _TypeVisitor.visitParameterElement
package:analyzer/src/dart/element/element.dart 6109:15  ParameterElementImpl.accept
package:analyzer/src/dart/element/element.dart 2565:13  ElementImpl.visitChildren
package:analyzer/dart/element/visitor.dart 333:13       RecursiveElementVisitor.visitMethodElement
package:mockito/src/builder.dart 290:11                 _TypeVisitor.visitMethodElement
package:analyzer/src/dart/element/element.dart 5320:54  MethodElementImpl.accept
package:analyzer/src/dart/element/element.dart 2565:13  ElementImpl.visitChildren
package:analyzer/dart/element/visitor.dart 237:13       RecursiveElementVisitor.visitClassElement
package:mockito/src/builder.dart 272:11                 _TypeVisitor.visitClassElement
package:analyzer/src/dart/element/element.dart 515:20   ClassElementImpl.accept
package:mockito/src/builder.dart 179:20                 MockBuilder._resolveAssetUris.addTypesFrom
package:mockito/src/builder.dart 187:9                  MockBuilder._resolveAssetUris.addTypesFrom
package:mockito/src/builder.dart 187:9                  MockBuilder._resolveAssetUris.addTypesFrom
package:mockito/src/builder.dart 192:7                  MockBuilder._resolveAssetUris
package:mockito/src/builder.dart 91:29                  MockBuilder.build

[INFO] Build:Running build completed, took 14.9s

[INFO] Build:Caching finalized dependency graph...
[INFO] Build:Caching finalized dependency graph completed, took 299ms

[SEVERE] Build:
Failed after 15.3s

How to resolve, any workarounds for this?