fix: Had to also check for generic type in return of a function.

add check to prevent stack overflow error
Add panic to prevent any other occurrences of stack overflow

examples/acceptance_tests/068/lib/tests.ak

@@ -106,5 +106,5 @@ test flatten_with_2() {
         None
       }
     },
-  ) == [("b", ""), ("a", "2")]
+  ) == [("a", "2"), ("b", "")]
 }