Crash application when close mediastream during remote accept phone call.

[tranductam2802]

When remote accept phone call, local perform hangup and disconnect to remote. The first, local check mediastream not null and are opened. Local call close method and get Null pointer exception after that.

Reproduce step:

• A call to B.
• B accept call.
• A press cancel button.

Actual:

• A crash application.

Expect:

• Check null before call.

Exception information:

io.skyway.skw_sample E/AndroidRuntime: FATAL EXCEPTION: io.skyway.peer.handler
    Process: io.skyway.skw_sample, PID: 17485
    method 'void io.skyway.Peer.Peer.queueWSMessage(org.json.JSONObject)' on a null object reference
    at io.skyway.Peer.BaseConnection$4.run(BaseConnection.java:867)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.os.HandlerThread.run(HandlerThread.java:61)

Reason:

this.provider.handler.postDelayed(new Runnable() {
        public void run() {
            if(null != BaseConnection.this._jsonOffer) {
                BaseConnection.this.provider.queueWSMessage(BaseConnection.this._jsonOffer);
                BaseConnection.this._jsonOffer = null;
            }
         }
}, 500L);

When remote accept phone call. this code above will be called. This code delay for 0.5 second and if local call close() method during this time, BaseConnection.this.provider will be clear. Only BaseConnection.this._jsonOffer had been checked null. Therefore, Null pointer exception occurred.