gh-148119: Refactor get_type_attr_as_size to improve error handling in structseq.c

Author: Wulian233

Objects/structseq.c

@@ -28,13 +28,23 @@ static Py_ssize_t
 get_type_attr_as_size(PyTypeObject *tp, PyObject *name)
 {
     PyObject *v = PyDict_GetItemWithError(_PyType_GetDict(tp), name);
-    if (v == NULL && !PyErr_Occurred()) {
+
+    if (v == NULL) {
+        if (PyErr_Occurred()) {
+            return -1;
+        }
         PyErr_Format(PyExc_TypeError,
                      "Missed attribute '%U' of type %s",
                      name, tp->tp_name);
         return -1;
     }
-    return PyLong_AsSsize_t(v);
+
+    Py_ssize_t result = PyLong_AsSsize_t(v);
+    if (result == -1 && PyErr_Occurred()) {
+        return -1;
+    }
+
+    return result;
 }
 
 #define VISIBLE_SIZE(op) Py_SIZE(op)