I am not sure we want to fix this actually. We've been moving in the opposite direction with other filters lately (e.g. filterFilter and orderBy throwing if not passed an array).

In any case, I think it's better to either explicitly throw (as with other filters) or return the input unchanged, if it's not a string.

I am leaning towards not making this change, but I am fine if enough people wants this change

@lgalfaso, do you think we should explicitly throw (a la https://github.com/angular/angular.js/blob/v1.5.0-rc.0/src/ng/filter/filter.js#L136) ?

@gkalpak with the right BC notice, yes, I think that that way is much better

OK @gkalpak - let's go with throwing in non-sensical cases...

Closing in favor of #13693.
@lgalfaso, @petebacondarwin, feel free to take a look at #13693 😄