不能为NUll

src/controller/room/assistant.js

@@ -87,7 +87,7 @@ export class RoomAssistant {
       const isAssistant = cancel ? 0 : 1;
       //  assistant是助手，customer是普通角色，操作role会好些
       const userObj = Object.assign({}, user, { role: "customer", order: 1, isAssistant });
-      const roomObj = Object.assign({}, roomConfigRes, { assistantId: cancel ? null : user.userId });
+      const roomObj = Object.assign({}, roomConfigRes, { assistantId: cancel ? '' : user.userId });
       // console.log("setAssistant", userObj, roomObj);
       // console.error("roomObj", roomObj);
       await updateRoomUser(roomId, userId, userObj);
@@ -119,7 +119,7 @@ export class RoomAssistant {
 
   async getRoomAssistant(roomId) {
     const roomConfig = await getRoomConfig(roomId);
-    const assistantId = roomConfig.assistantId || null;
+    const assistantId = roomConfig.assistantId || '';
     return Promise.resolve(assistantId);
   }
   /**