fix: 修复无接壤城市数据展示的问题

src/main/java/mjkf/xinke/main/service/DataAdjacentService.java

@@ -90,7 +90,7 @@ public class DataAdjacentService extends DataService<BaseMapper<DataAdjacent>, D
                 this.saveOrUpdateByIndex(item);
             }
         }
-        return null;
+        return result;
      }
 }