First login with Android Nextcloud App on a Samsung Galaxy crash

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. Install Android Nextcloud app from Google Play Store
2. Set host URL
3. Login to the host
4. Crash with error message

### Expected behaviour

After login the Nextcloud app should load all files and documents promptly for the user that just logged in successfully.

### Actual behaviour

After successful login, Android Nextcloud app crashes and the error message shows up.

### Android version

Android 10 (see logs below)

### Device brand and model

Samsung Galaxy A7

### Stock or custom OS?

Stock

### Nextcloud android app version

30340190

### Nextcloud server version

Nextcloud Hub 9 (30.0.13)

### Using a reverse proxy?

Yes

### Android logs

Cause of error
```
Exception in thread "main" java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.String com.nextcloud.client.account.User.getAccountName()' on a null object reference
at com.owncloud.android.ui.activity.FileDisplayActivity.onStart(FileDisplayActivity.kt:2810)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1433)
at android.app.Activity.performStart(Activity.java:7978)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3580)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:183)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:132)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7948)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)

```
App information
ID: com.nextcloud.client
Version: 30340190
Build flavor: gplay

Device information
Brand: samsung
Device: a7y18lte
Model: SM-A750FN
Id: QP1A.190711.020
Product: a7y18ltexx

Firmware
SDK: 29
Release: 10
Incremental: A750FNXXU5CVG2

### Server error logs

```bash

```

### Additional information

This issue is similar to #15831 , #15771 and #16078 but happening on a different model of smartphone with different software versions.
Also, this issue makes it impossible to setup account login to the Android Nextcloud Notes app (which needs a similar login, also failing).