Fall back to the main page when rotating the screen on the About page

[Terrible-Tornado]

Environment

Android Version: 9.0
App Version: 1.4.1
Device: Google Pixel 2

Step to reproduce

1. Open navigation drawer
2. Enter the About page
3. Rotate the screen and the issue appears

ScreenRecord

test.mp4

Logcat

FATAL EXCEPTION: main
Process: org.secuso.privacyfriendlynotes, PID: 22558
java.lang.RuntimeException: Unable to start activity ComponentInfo{org.secuso.privacyfriendlynotes/org.secuso.privacyfriendlynotes.ui.AboutActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.ActivityThread.handleRelaunchActivityInner(ActivityThread.java:4784)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4693)
at android.app.servertransaction.ActivityRelaunchItem.execute(ActivityRelaunchItem.java:69)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at org.secuso.privacyfriendlynotes.ui.AboutActivity.onCreate(AboutActivity.java:36)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
at android.app.ActivityThread.handleRelaunchActivityInner(ActivityThread.java:4784) 
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4693) 
at android.app.servertransaction.ActivityRelaunchItem.execute(ActivityRelaunchItem.java:69) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:193) 
at android.app.ActivityThread.main(ActivityThread.java:6669) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)