ERR_DATA_CHANNEL error will be throw by SimplePeer and application level code cannot catch it.

[milochen0418]

The SimpleSignalClient code will receive error randomly if another peer's website page refresh .

After checking this problem, we cannot catch this error.

Right now we can avoid this issue it by this way

Because we cannot catch this error, so I try to avoid to throw it when ERR_DATA_CHANNEL error happen.

So we can at least implement dynamically peer remove/add in the room.

[milochen0418]

The RTCErrorEvent will be throw as err in events/events.js if we don't handle peer('error').
So I put it in client code.

 
peer.on('error', (err)=>{
  console.log(err)
})

This is issue is solve by this pull request
#36