Data Path builder app-shell should have required property class

Schema validation failed with the following errors:
Data path ".builders['app-shell']" should have required property 'class'.
Error: Schema validation failed with the following errors:
Data path ".builders['app-shell']" should have required property 'class'.
at MergeMapSubscriber.project (C:\AngularCRUD\node_modules\@angular-devkit\core\src\workspace\workspace.js:210:42)
at MergeMapSubscriber._tryNext (C:\AngularCRUD\node_modules\rxjs\internal\operators\mergeMap.js:65:27)
at MergeMapSubscriber._next (C:\AngularCRUD\node_modules\rxjs\internal\operators\mergeMap.js:55:18)
at MergeMapSubscriber.Subscriber.next (C:\AngularCRUD\node_modules\rxjs\internal\Subscriber.js:64:18)
at MergeMapSubscriber.notifyNext (C:\AngularCRUD\node_modules\rxjs\internal\operators\mergeMap.js:84:26)
at InnerSubscriber._next (C:\AngularCRUD\node_modules\rxjs\internal\InnerSubscriber.js:25:21)
at InnerSubscriber.Subscriber.next (C:\AngularCRUD\node_modules\rxjs\internal\Subscriber.js:64:18)
at MapSubscriber._next (C:\AngularCRUD\node_modules\rxjs\internal\operators\map.js:52:26)
at MapSubscriber.Subscriber.next (C:\AngularCRUD\node_modules\rxjs\internal\Subscriber.js:64:18)
at SwitchMapSubscriber.notifyNext (C:\AngularCRUD\node_modules\rxjs\internal\operators\switchMap.js:77:26)