Crash when returning to UI a day later after playing video: NPE via `ExtendedListFragment.onCreateOptionsMenu`

### Steps to reproduce
1. Start app, navigate to video stored locally
2. Watch the video
3. Dont close the video but keep on doing other stuff
4. return to ui to watch another video (in my case a day later)
5. ui is showing still of previous video but is unresponsive and crashes eventually

### Expected behaviour
- Either show the Filesystem or continue with the old video

### Actual behaviour
- App crashes when trying to continue to play the video

### Can you reproduce this problem on https://try.nextcloud.com?
- Please create a test demo account and see if this still happens there.
- If yes, please open up a bug report
- If not, please verify server setup and ask for help on forum

### Environment data
I'm using my tablet, will add these details later when at my PC
Android version:

Device model:

Stock or customized system:

Nextcloud app version:

Nextcloud server version:

Reverse proxy:

### Logs
#### Web server error log
```
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#### Nextcloud log (data/nextcloud.log)
```
Insert your Nextcloud log here
```
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