How to properly make mock throw an error in Jest?

Change .mockReturnValue with .mockImplementation:

yourMockInstance.mockImplementation(() => {
  throw new Error();
});

If it's a promise you can also to .rejects www.jestjs.io/docs/en/asynchronous#resolves--rejects

For Angular + Jest:

import { throwError } from 'rxjs';

yourMockInstance.mockImplementation(() => {
  return throwError(new Error('my error message'));
});

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