Crash on startup when requesting permissions

[TimPushkin]

The app may crash on startup if it lacks some permissions with the following exception:

2022-08-12 20:47:29.340 3992-3992/com.opencamera_sensors.app E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.opencamera_sensors.app, PID: 3992
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.opencamera_sensors.app/net.sourceforge.opencamera.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void net.sourceforge.opencamera.PermissionHandler.onRequestPermissionsResult(int, int[])' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4031)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4197)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2434)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loopOnce(Looper.java:226)
        at android.os.Looper.loop(Looper.java:313)
        at android.app.ActivityThread.main(ActivityThread.java:8633)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:567)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1133)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void net.sourceforge.opencamera.PermissionHandler.onRequestPermissionsResult(int, int[])' on a null object reference
        at net.sourceforge.opencamera.MainActivity.onRequestPermissionsResult(MainActivity.java:5647)
        at android.app.Activity.requestPermissions(Activity.java:5355)
        at androidx.core.app.ActivityCompat.requestPermissions(ActivityCompat.java:502)
        at net.sourceforge.opencamera.MainActivity.onCreate(MainActivity.java:234)
        at android.app.Activity.performCreate(Activity.java:8282)
        at android.app.Activity.performCreate(Activity.java:8262)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1329)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4005)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4197) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2434) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loopOnce(Looper.java:226) 
        at android.os.Looper.loop(Looper.java:313) 
        at android.app.ActivityThread.main(ActivityThread.java:8633) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:567) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1133)

Tis probably happens because some permissions are requested before the permission handler is initialized.