gh-111789: Use PyDict_GetItemRef() in Modules/_csv.c (gh-112073)

Author: serhiy-storchaka

Modules/_csv.c

@@ -160,15 +160,9 @@ static PyObject *
 get_dialect_from_registry(PyObject *name_obj, _csvstate *module_state)
 {
     PyObject *dialect_obj;
-
-    dialect_obj = PyDict_GetItemWithError(module_state->dialects, name_obj);
-    if (dialect_obj == NULL) {
-        if (!PyErr_Occurred())
-            PyErr_Format(module_state->error_obj, "unknown dialect");
+    if (PyDict_GetItemRef(module_state->dialects, name_obj, &dialect_obj) == 0) {
+        PyErr_SetString(module_state->error_obj, "unknown dialect");
     }
-    else
-        Py_INCREF(dialect_obj);
-
     return dialect_obj;
 }