add runtime type for wrapped records

Author: bentsku

src/py_avro_schema/_schemas.py

@@ -312,16 +312,19 @@ def _wrap_as_record(self, inner_schema: JSONObj, names: NamesType) -> JSONType:
         if fullname in names:
             return fullname
         names.append(fullname)
+
+        fields = [
+            {"name": REF_ID_KEY, "type": ["null", "long"], "default": None},
+            {"name": REF_DATA_KEY, "type": inner_schema},
+        ]
+        if Option.ADD_RUNTIME_TYPE_FIELD in self.options:
+            fields.append({"name": RUNTIME_TYPE_KEY, "type": ["null", "string"]})
+
         record_schema = {
             "type": "record",
             "name": record_name,
-            "fields": [
-                {"name": REF_ID_KEY, "type": ["null", "long"], "default": None},
-                {"name": REF_DATA_KEY, "type": inner_schema},
-            ],
+            "fields": fields,
         }
-        if Option.ADD_RUNTIME_TYPE_FIELD in self.options:
-            record_schema["fields"].append({"name": RUNTIME_TYPE_KEY, "type": ["null", "string"]})
 
         if self.namespace:
             record_schema["namespace"] = self.namespace