Player.html gives alert error message "data_channel_error" when playing is stopped

[Canates Arikan]

Describe the bug
When playing a webrtc stream with player.html if you stop playing with stop button, you get a data_channel_error alert which you should press to continue.

Expected behavior
If you press stop button, you should not get a data_channel_error alert because there is no error for the user. Data Channel should be closed gracefully.

Desktop (please complete the following information):

• Browser Chrome
  (For Firefox you dont get the alert)

[Canates Arikan]

Same error occurs also for stop publishing button in index.html.

One solution would be handling "data_channel_error" inside callbackError instead of giving an alert and closing data channels before this error occurs if possible.