Bulk editing song metadata clears track numbers

[iztokbajcar]

Describe the bug
When editing metadata of multiple songs at once (e.g. changing genre), the track number of all those song is cleared even if it is set to "Leave unchanged".

To reproduce
Steps to reproduce the behavior:

1. Select two or more songs
2. Right click, then click on 'Edit...'
3. Alter the value of one of the fields other than Track (e.g. Genre) while leaving the Track field on 'Leave unchanged'
4. Click 'Update'

Expected behavior
The songs' track info should remain unchanged, as indicated by the 'Leave unchanged' value.

Screenshots
Before editing:

Metadata edit example (Genre was changed to 'Rock'):

The state after editing the songs:

Environment

• Koel version: 6.12.0
• OS: Arch Linux
• Browser: Firefox 121.0
• PHP version: 8.1.8
• Node version: N/A

Additional context
The server is running as a Docker container.