The method where does only exist in Illuminate\Database\Eloq...nate\Support\Collection, but not in App\Model\ArticleCategory.
It seems like the method you are trying to call exists only in some of the
possible types.
Let’s take a look at an example:
classA{publicfunctionfoo(){}}classBextendsA{publicfunctionbar(){}}/** * @param A|B $x */functionsomeFunction($x){$x->foo();// This call is fine as the method exists in A and B.$x->bar();// This method only exists in B and might cause an error.}