The App Crashes On Clicking Settings and Rotating The Screen

Expected behavior

On rotating the screen or changing the orientation of the screen the app should show the same page and must be stable and not crash.

Actual behavior

But the app crashes on clicking the Settings option and rotating the screen of the page to view in landscape mode.

How to reproduce

1. Install the app from F-Droid.
   
2. Launch the app. Click on settings from left navigation menu.
   
3. Change the orientation of the screen to landscape mode and rotate the screen.
   
4. The app will show a crash showing dialogue box to you and will stop functioning.
   

• Device: Samsung Galaxy J5
  
• Operating System: Android 6.0.1
  
• App Version: 1.2.1

Recording Of The Bug

Here's a video recording of the bug.