This error occurs in Angular when you have copied a module or component but you did not rename the class properly.
Solution
Make sure the components module file has the right "export class xModule" function inside xModule.ts.
A second solution is that you possibly want to import a component inside another component. Make sure you import the module, rather than the component. So:
imports: [EventcardModule,
Instead of
imports: [EventcardComponent,