Wait for closeWaitChannel in OnClose hook.

internal/data_channel.go

@@ -144,11 +144,7 @@ func (conn *DataChannel) init() {
 	})
 
 	conn.dataChannel.OnClose(func() {
-		select {
-		case conn.closeWaitChannel <- nil:
-		default:
-		}
-
+		conn.closeWaitChannel <- nil
 		conn.triggerClose()
 	})
 }