First login with Android Nextcloud App on a Samsung Galaxy crash

[YoannPa]

⚠️ Before posting ⚠️

• This is a bug, not a question or an enhancement.
• I've searched for similar issues and didn't find a duplicate.
• I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
• I agree to follow Nextcloud's 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

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).