Angular NgRx - uncaught typeerror - cannot read Property 'Entities' of undefined

Yesterday, we had flickering tests in our Angular application, which uses NgRx. Hopping from one test to the next and even sometimes running green, we had this error:

Uncaught TypeError: Cannot read property 'entities' of undefined

Here’s the simple solution: Destroy the fixture after each test:

afterEach(() => {
  fixture.destroy();
});