I played a file via drag'n'drop earlier, then deleted that file.
Now I re-downloaded the track and Mixxx hits this debug assertion, both when rescanning music directories and when dragging the track onto a deck.
After the crash I checked if the previous file is in Missing -- it's not.
Noticed when testing modplug fix PR https://github.com/mixxxdj/mixxx/pull/4736 with this track:
https://www.infect-rules.de/2019/12/27/beathoven-infect-back-on-track-module-released-xmas-2019/
Happens with main, too.
debug [LibraryScanner 1] LibraryScanner - slotStartScan()
info [LibraryScanner 1] LibraryScanner - Cleaning up database...
info [LibraryScanner 1] LibraryScanner - Deleted 5 orphaned directory hashes
info [LibraryScanner 1] LibraryScanner - Finished database cleanup: 22 ms
debug [LibraryScanner 1] LibraryScanner - Recursively scanning library.
debug [LibraryScanner 1] SqlTransaction - Started new SQL database transaction on "MIXXX-2"
debug [Thread (pooled)] Importing track "/home/me/Music/beathoven_back-on-track.mod"
debug [LibraryScanner 1] GlobalTrackCache - Resolving track by canonical location "/home/me/Music/beathoven_back-on-track.mod"
debug [LibraryScanner 1] GlobalTrackCache - Cache miss - allocating track TrackRef {"/home/me/Music/beathoven_back-on-track.mod","/home/me/Music/beathoven_back-on-track.mod",-1}
debug [LibraryScanner 1] GlobalTrackCache - Cache miss - inserting new track into cache TrackRef {"/home/me/Music/beathoven_back-on-track.mod","/home/me/Music/beathoven_back-on-track.mod",-1} QObject(0x0)
info [LibraryScanner 1] Unable to detect MIME type from file "/home/me/Music/beathoven_back-on-track.mod"
info [LibraryScanner 1] Unable to detect MIME type from file "/home/me/Music/beathoven_back-on-track.mod"
debug [LibraryScanner 1] SoundSourceProxy - SoundSourceProvider "MODPlug" created a SoundSource for file "file:///home/me/Music/beathoven_back-on-track.mod" of type "Protracker"
debug [LibraryScanner 1] SoundSourceProxy - Initializing track metadata and embedded cover art from file "file:///home/me/Music/beathoven_back-on-track.mod"
info [LibraryScanner 1] SeratoMarkers2 - Reading bpmlock state from 'Serato Markers2' tag data...
debug [LibraryScanner 1] Reading cues from 'Serato Markers2' tag data...
DEBUG ASSERT: "sourceSynchronizedAt.timeSpec() == Qt::UTC" in function bool mixxx::TrackRecord::replaceMetadataFromSource(mixxx::TrackMetadata&&, const QDateTime&) at /home/me/Downloads/mixxx_source/src/master/src/track/trackrecord.cpp:194
Aborted (core dumped)
https:/