[Bug]: Error removing folder that stops the synchronisation

⚠️ Before submitting, please verify the following: ⚠️

[x] This is a bug, not a question or a configuration issue.
[x] This issue is not already reported on Github (I've searched it).
[x] Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
[x] I agree to follow Nextcloud's Code of Conduct

Bug description

When a user synchronises a read-only file deletion, the modification is not applied and the synchronisation stops.

There is no error message written on the synchronisation box (it is only possible to see it by looking at the client logs). It makes it really harder to see that there is a synchronisation problem. Perhaps I should open another issue related to the absence of error display for the end-user.

By contrast with issue https://github.com/nextcloud/desktop/issues/6884 also related to problem of synchronisation due to folder permissions, this issue is related to files permissions (and for MacOS).

Steps to reproduce

Set up a synchronisation for userA to a read-only shared folder.
User B with write permission on the folder delete a file inside this folder.
User A do the synchronisation. After the preparation step, the synchronisation stops without error (but nothing is synchronised).

Expected behavior

At step 3 before, the file should be deleted locally and the synchronisation should not stop.

Which files are affected by this bug

Drive_Clients/file.xlsx

Operating system

macOS

Which version of the operating system you are running.

MacOS

Package

Official macOS 12+ universal pkg

Nextcloud Server version

29.0.7.1

Nextcloud Desktop Client version

3.14.1daily

Is this bug present after an update or on a fresh install?

Updated to a major version (ex. 3.3.6 to 3.4.0)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

Are you using an external user-backend?

[ ] Default internal user-backend
[x] LDAP/ Active Directory
[ ] SSO - SAML
[ ] Other

Nextcloud Server logs

No response

Additional info

This is an extract of the log file. The bug has been triggered by two different Mac users in our organisation.

2024-10-08 14:24:57:809 [ info nextcloud.sync.engine /var/folders/yr/XXXXX/T/macos-26086/src/libsync/syncengine.cpp:787 ]:  #### Discovery end ####################################################  10935 ms
2024-10-08 14:24:57:809 [ debug nextcloud.sync.database /var/folders/yr/XXXXX/T/macos-26086/src/common/syncjournaldb.cpp:3062 ] [ OCC::SyncJournalDb::commitInternal ]: Transaction commit "Post discovery" and starting new transaction
2024-10-08 14:24:57:810 [ info nextcloud.gui.folder /var/folders/yr/XXXXX/T/macos-26086/src/gui/folder.cpp:1678 ]:  will delete invalid read-only folders: "Drive_Clients/file.xlsx"
2024-10-08 14:24:57:813 [ info nextcloud.gui.folder /var/folders/yr/XXXXX/T/macos-26086/src/gui/folder.cpp:887 ]:   Saved folder "1" to settings, status QSettings::NoError
2024-10-08 14:24:57:813 [ debug nextcloud.gui.socketapi /var/folders/yr/XXXXX/T/macos-26086/src/gui/socketapi/socketapi.cpp:228 ]   [ OCC::SocketListener::sendMessage ]:   Sending SocketAPI message --> "UPDATE_VIEW:/Users/XZXZ/Nextcloud" to QLocalSocket(0x600000d7d380)
2024-10-08 14:24:57:813 [ info nextcloud.gui.application /var/folders/yr/XXXXX/T/macos-26086/src/gui/owncloudgui.cpp:247 ]: Sync state changed for folder  "https://nc.resilio-solutions.com/remote.php/dav/files/XYXY/" :  "Sync paused"
2024-10-08 14:24:57:813 [ debug nextcloud.gui.socketapi /var/folders/yr/XXXXX/T/macos-26086/src/gui/socketapi/socketapi.cpp:228 ]   [ OCC::SocketListener::sendMessage ]:   Sending SocketAPI message --> "UNREGISTER_PATH:/Users/XZXZ/Nextcloud" to QLocalSocket(0x600000d7d380)
2024-10-08 14:24:57:813 [ warning nextcloud.sync.filesystem /var/folders/yr/XXXXX/T/macos-26086/src/libsync/filesystem.cpp:313 ]:   Error removing folder "/Users/XZXZ/Nextcloud/Drive_Clients/file.xlsx"
2024-10-08 14:24:57:813 [ info nextcloud.sync.engine /var/folders/yr/XXXXX/T/macos-26086/src/libsync/syncengine.cpp:1006 ]: User aborted sync
2024-10-08 14:24:57:813 [ info nextcloud.sync.engine /var/folders/yr/XXXXX/T/macos-26086/src/libsync/syncengine.cpp:918 ]:  Sync run took  10940 ms

nextcloud / desktop