App Keeps Crashing When Connecting

[AadityaRathod97]

so i am trying to connect to a tablet, i hope that works
i know this code is for microcontrollers

but whenever i try to connect the app keeps crashing and gives me this error

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.ahmedabdelmeged.bluetoothmcsample, PID: 5505
java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter aVoid
at com.ahmedabdelmeged.bluetoothmc.BluetoothMC$ConnectBT.onPostExecute(BluetoothMC.kt)
at com.ahmedabdelmeged.bluetoothmc.BluetoothMC$ConnectBT.onPostExecute(BluetoothMC.kt:155)
at android.os.AsyncTask.finish(AsyncTask.java:662)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:679)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5468)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:671)