BUG: fix resource cleanup order in ufunc.at impl

Author: ngoldbaum

numpy/_core/src/umath/ufunc_object.c

@@ -5941,7 +5941,6 @@ ufunc_at(PyUFuncObject *ufunc, PyObject *args)
     NPY_AUXDATA_FREE(auxdata);
 
     Py_XDECREF(op2_array);
-    Py_XDECREF(iter);
     Py_XDECREF(iter2);
     for (int i = 0; i < nop; i++) {
         Py_XDECREF(operation_descrs[i]);
@@ -5957,9 +5956,12 @@ ufunc_at(PyUFuncObject *ufunc, PyObject *args)
         if (PyArray_FLAGS(op1_array) & NPY_ARRAY_WRITEBACKIFCOPY) {
             PyArray_DiscardWritebackIfCopy(op1_array);
         }
+        // iter might own the array, so it must be decref'd second
+        Py_XDECREF(iter);
         return NULL;
     }
     else {
+        Py_XDECREF(iter);
         Py_RETURN_NONE;
     }
 }