address review and add assert

Author: Sacul0457

Modules/_testinternalcapi/test_cases.c.h

@@ -3921,6 +3921,7 @@ dummy_func(
 
         op(_CHECK_FUNCTION_VERSION, (func_version/2, callable, unused, unused[oparg] -- callable, unused, unused[oparg])) {
             PyObject *callable_o = PyStackRef_AsPyObjectBorrow(callable);
+            assert(PyFunction_Check(callable_o));
             PyFunctionObject *func = (PyFunctionObject *)callable_o;
             EXIT_IF(func->func_version != func_version);
         }