bpo-41204: Fix compiler warning in ast_type_init() (GH-21307)

diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index b93906b..6fe44b9 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -688,13 +688,14 @@
 static int
 ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
 {
+    astmodulestate *state = get_global_ast_state();
+    if (state == NULL) {
+        return -1;
+    }
+
     Py_ssize_t i, numfields = 0;
     int res = -1;
     PyObject *key, *value, *fields;
-    astmodulestate *state = get_global_ast_state();
-    if (state == NULL) {
-        goto cleanup;
-    }
     if (_PyObject_LookupAttr((PyObject*)Py_TYPE(self), state->_fields, &fields) < 0) {
         goto cleanup;
     }