move error case up

Author: Fidget-Spinner

Python/bytecodes.c

@@ -808,9 +808,9 @@ dummy_func(
             DEAD(right);
             PyStackRef_CLOSE_SPECIALIZED(left, _PyUnicode_ExactDealloc);
             DEAD(left);
+            *target_local = PyStackRef_NULL;
             ERROR_IF(temp == NULL);
             res = PyStackRef_FromPyObjectSteal(temp);
-            *target_local = PyStackRef_NULL;
         }
 
        op(_GUARD_BINARY_OP_EXTEND, (descr/4, left, right -- left, right)) {