DataconnectionのsendでNullPointerExceptionが発生

【発生事象】
DataConnection.send() で NullPointerException

【環境】
・OS：Android 9.0


【ログ】
2020-07-23 01:08:13.292 4431-4431/net.nishidentsu.teleark2 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: net.nishidentsu.teleark2, PID: 4431
    java.lang.NullPointerException: Attempt to invoke virtual method 'int io.skyway.Peer.BaseConnection$SerializationEnum.ordinal()' on a null object reference
        at io.skyway.Peer.DataConnection.send(DataConnection.java:202)
        at net.nishidentsu.teleark2.MainActivity$setSkywayCallback$1$2$1$1.run(MainActivity.kt:720)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:280)
        at android.app.ActivityThread.main(ActivityThread.java:6710)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)