Custom Keyboard:The specified message queue synchronization barrier token has not been posted or has already been remove

Question

I have made a custom keyboard, recently it crashed with this log randomly,

2020-07-03 16:30:53.529 11538-11538/com.nisarg.nboard E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.nisarg.nboard, PID: 11538
    java.lang.IllegalStateException: The specified message queue synchronization  barrier token has not been posted or has already been removed.
        at android.os.MessageQueue.removeSyncBarrier(MessageQueue.java:520)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1433)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6899)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1029)
        at android.view.Choreographer.doCallbacks(Choreographer.java:841)
        at android.view.Choreographer.doFrame(Choreographer.java:772)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1015)
        at android.os.Handler.handleCallback(Handler.java:794)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:176)
        at android.app.ActivityThread.main(ActivityThread.java:6635)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

I don't know why this error occured, or due to which part of my code, could someone help me with this?