[3.13] gh-148157: Check for _PyPegen_add_type_comment_to_arg fail in _PyPegen_name_default_pair (GH-148158) (#148163)

(cherry picked from commit 1795fccfbc)

Co-authored-by: Stan Ulbrych <stan@python.org>

Parser/action_helpers.c

@@ -434,6 +434,9 @@ _PyPegen_name_default_pair(Parser *p, arg_ty arg, expr_ty value, Token *tc)
         return NULL;
     }
     a->arg = _PyPegen_add_type_comment_to_arg(p, arg, tc);
+    if (!a->arg) {
+        return NULL;
+    }
     a->value = value;
     return a;
 }