Enhance callback handling in SocketUser class to ensure callback is a function before invocation, preventing potential runtime errors.

src/socket/socketuser.js

@@ -174,16 +174,20 @@ export class SocketUser {
       data.objectType,
       data.filter
     );
+    if (typeof callback === 'function') {
       callback({ success: true });
     }
+  }
 
   async handleSubscribeToObjectUpdateEvent(data, callback) {
     const result = await this.updateManager.subscribeToObjectUpdate(
       data._id,
       data.objectType
     );
+    if (typeof callback === 'function') {
       callback(result);
     }
+  }
 
   async handleSubscribeToObjectEventEvent(data) {
     await this.eventManager.subscribeToObjectEvent(