Android NativeCall app: getMediaDescription returns null

Trying to run a call, and sometimes tapping the "call" button in the application is making the app to crash as the native call returns a null object. See the stacktrace:

01-29 10:50:55.224 2228-2228/com.ericsson.research.owr.examples.nativecall E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.ericsson.research.owr.examples.nativecall, PID: 2228
java.lang.NullPointerException
at com.ericsson.research.owr.examples.nativecall.PeerHandler.handleSessionDescription(PeerHandler.java:275)
at com.ericsson.research.owr.examples.nativecall.PeerHandler.onMessage(PeerHandler.java:115)
at com.ericsson.research.owr.examples.nativecall.SignalingChannel$PeerChannel.onMessage(SignalingChannel.java:256)
at com.ericsson.research.owr.examples.nativecall.SignalingChannel$PeerChannel.access$1000(SignalingChannel.java:219)
at com.ericsson.research.owr.examples.nativecall.SignalingChannel.handleEvent(SignalingChannel.java:169)
at com.ericsson.research.owr.examples.nativecall.SignalingChannel.access$900(SignalingChannel.java:52)
at com.ericsson.research.owr.examples.nativecall.SignalingChannel$2.run(SignalingChannel.java:156)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:146)