NPE on dev.onvoid.webrtc.RTCPeerConnection.getConnectionState on closed connection

[thelsing]

Describe the bug
After the RTCPeerConnection is closed, calls to getConnectionState() throw a NPE.

To Reproduce
Steps to reproduce the behavior:

1. Establish a RTCPeerConnection
2. Close it.
3. Call getConnectionsState()
4. See NPE.

Expected behavior
Simple state methods should return a default value if the native object was discarded. In this case RTCPeerConnectionState.CLOSED or DISCONNECTED.

[devopvoid]

Thanks for the report, @thelsing !

Will fix that ASAP