crash on Account login

### ⚠️ 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

New install on Android 16, pixel 9a
Login to my own server in home network, crash

### Expected behaviour

No crash

### Actual behaviour

### Cause of error
```java
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:2784)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1699)
at android.app.Activity.performStart(Activity.java:9287)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:4344)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:214)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:194)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:176)
at android.app.servertransaction.TransactionExecutor.executeNonLifecycleItem(TransactionExecutor.java:129)
at android.app.servertransaction.TransactionExecutor.executeTransactionItems(TransactionExecutor.java:103)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:80)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2830)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.dispatchMessage(Looper.java:315)
at android.os.Looper.loopOnce(Looper.java:251)
at android.os.Looper.loop(Looper.java:349)
at android.app.ActivityThread.main(ActivityThread.java:9041)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:929)

```

### App information
* ID: `com.nextcloud.client`
* Version: `30340090`
* Build flavor: `generic`

### Device information
* Brand: `google`
* Device: `tegu`
* Model: `Pixel 9a`
* Id: `BP3A.250905.014`
* Product: `tegu`

### Firmware
* SDK: `36`
* Release: `16`
* Incremental: `13873947`

### Android version

16

### Device brand and model

pixel 9a

### Stock or custom OS?

Stock

### Nextcloud android app version

3.34.0

### Nextcloud server version

31.0.8

### Using a reverse proxy?

No

### Android logs

_No response_

### Server error logs

```bash

```

### Additional information

_No response_