I had this error when I was binding an array of values in form builder the wrong way.
What I did:
fb.group({items: [1, 2, 3, 4]})
How it should be:
fb.group({items: [[1, 2, 3, 4]]})
You have to wrap everything into an array, otherwise angular thinks that [1, 2, 3, 4] is a form control definition rather than a form control value.