bug: No local files added when a folder contains non-media files

[ghaspias]

System Details
OS: Windows 10
Arch: x64
Version: v3.3.0, v3.4.0
Installed by: GitHub MSI

Describe the bug
When adding a folder containing music files (e.g. mp3) along with other files (jpg cover images, desktop.ini) from my local machine, either by drag'n'drop from the browse panel or from the file manager, or by clicking on the '+' button, no tracks are added and a message says "Unable to add local files. No suitable files found."
If I select only the music files and drag them, they are added correctly to the queue.

Expected behavior
Non media files should be ignored when attempting to add to the queue, but valid media should still be added.

[ghaspias]

I'm sorry for using AI, but it sometimes saves time...
According to deepwiki, the problem is:

When a folder is added, the code assigns the result of listFiles() to useable using the = operator instead of +=:

if (d.exists()) {  
    useable = listFiles(d, useServer, useLocal, handlers);  // Line 295  
}

This overwrites any previously collected files instead of appending them playqueuemodel.cpp:290-296 . In contrast, when processing playlist files, the code correctly uses += to append:

else if (checkExtension(u.path(), constM3uPlaylists)) {  
    useable += expandM3uPlaylist(u.path(), useServer, useLocal, handlers);  // Line 298  
}

[maxmitti]

I don’t see how non-music files in the selection would cause the issue, but I could reproduce it simply by selecting and dragging two folders to the playlist. Only the last folder is actually added, which is exactly due to the issue you found with the AI.

Hopefully fixing it will also fix what you observed.