fix: 沙箱不能发图片，收chanel消息提示

Author: myZhangDong

demo/src/config/WebIMConfig.js

@@ -110,8 +110,8 @@ var config = {
     /**
      * enable localstorage for history messages. For use in this demo
      */
-    enableLocalStorage: true,
+    enableLocalStorage: true
 
-    deviceId: 'newDevice'
+    // deviceId: 'newDevice'
 }
 export default config

demo/src/config/websdk3.4.1.js

@@ -422,7 +422,8 @@ WebIM.conn.listen({
     },
     onCustomMessage: msg => {
         console.log('onCustomMessage', msg)
-    }
+    },
+    onChannelMessage: msg => console.log('onChannelMessage', msg)
 })
 
 /* ------------- Types and Action Creators ------------- */