java.lang.NullPointerException in OfflineSyncWork.checkEtagChanged line 140

[hasezoey]

⚠️ 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

it happens in a background task

Expected behaviour

probably no error

Actual behaviour

a error is logged

02-02 13:07:33.077  3991  4038 E CheckEtagRemoteOperation: Error while retrieving eTag
02-02 13:07:33.077  3991  4038 D OfflineSyncJob: /: eTag changed
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: Work [ id=1978cd15-2514-4729-9d89-d67a22ebbfc0, tags={ timestamp:1675177395832, com.nextcloud.client.jobs.OfflineSyncWork, *, name:periodic_offline_sync } ] failed because it threw an exception/error
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: java.util.concurrent.ExecutionException: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.ArrayList.get(int)' on a null object reference
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at androidx.work.impl.utils.futures.AbstractFuture.getDoneValue(AbstractFuture.java:516)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at androidx.work.impl.utils.futures.AbstractFuture.get(AbstractFuture.java:475)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at androidx.work.impl.WorkerWrapper$2.run(WorkerWrapper.java:311)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at androidx.work.impl.utils.SerialExecutor$Task.run(SerialExecutor.java:91)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at java.lang.Thread.run(Thread.java:1012)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.ArrayList.get(int)' on a null object reference
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at com.nextcloud.client.jobs.OfflineSyncWork.checkEtagChanged(OfflineSyncWork.kt:140)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at com.nextcloud.client.jobs.OfflineSyncWork.recursive(OfflineSyncWork.kt:79)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at com.nextcloud.client.jobs.OfflineSyncWork.doWork(OfflineSyncWork.kt:64)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	at androidx.work.Worker$1.run(Worker.java:86)
02-02 13:07:33.079  3991  4011 E WM-WorkerWrapper: 	... 3 more
02-02 13:07:33.080  3991  4011 I WM-WorkerWrapper: Worker result FAILURE for Work [ id=1978cd15-2514-4729-9d89-d67a22ebbfc0, tags={ timestamp:1675177395832, com.nextcloud.client.jobs.OfflineSyncWork, *, name:periodic_offline_sync } ]

Android version

13

Device brand and model

OnePlus 9 Pro

Stock or custom OS?

Custom (explain in "additional information")

Nextcloud android app version

3.23.1

Nextcloud server version

None (error happened when server is not online)

Using a reverse proxy?

Yes

Android logs

logcatOutput.txt
Note: log has been edited to remove references to actual server / ip's (and also somewhat personal data like directory names)

Server error logs

None (no server was running)

Additional information

i had noticed this error while investigating something unrelated to nextcloud, and i am reporting it because this error does not seem like it should be happening

probably:

android/app/src/main/java/com/nextcloud/client/jobs/OfflineSyncWork.kt

Line 140 in 8cc3bd1

result.data[0] as String

Custom (explain in "additional information")

LineageOS 20 (20.0-20230131)