gh-125843: fix test_curses.test_attributes on x86-64 macOS

Modules/_cursesmodule.c

@@ -392,17 +392,16 @@ _PyCursesStatefulCheckFunction(PyObject *module,
  */
 
 /*
- * Return None if 'code' is OK. Otherwise, set an exception
- * using curses_set_error() and the remaining arguments, and
- * return NULL.
+ * Return None if 'code' is different from ERR (implementation-defined).
+ * Otherwise, set an exception using curses_set_error() and the remaining
+ * arguments, and return NULL.
  */
 static PyObject *
 curses_check_err(PyObject *module, int code,
  const char *curses_funcname,
  const char *python_funcname)
 {
  if (code != ERR){
- assert(code == OK);
  Py_RETURN_NONE;
  }
  curses_set_error(module, curses_funcname, python_funcname);
@@ -416,7 +415,6 @@ curses_window_check_err(PyCursesWindowObject *win, int code,
  const char *python_funcname)
 {
  if (code != ERR){
- assert(code == OK);
  Py_RETURN_NONE;
  }
  curses_window_set_error(win, curses_funcname, python_funcname);
@@ -1580,7 +1578,7 @@ _curses_window_derwin_impl(PyCursesWindowObject *self, int group_left_1,
  win = derwin(self->win,nlines,ncols,begin_y,begin_x);
 
  if (win == NULL){
-curses_window_set_error(self, "derwin", NULL);
+curses_window_set_null_error(self, "derwin", NULL);
  return NULL;
  }