Crash when using Output splitting tool on big joblists

[umfuz]

Describe the bug
I'm trying to join my flac collection grouping the files by their metadata using the Output splitting tool. With big enough joblists (e.g. 1000 tracks) the app closes unexpectedly. This doesn't happen for small enough joblists (e.g. 100 tracks). I've tried the Flatpak stable and the AppImage stable and continuous releases. Also could reproduce the problem on Windows with the stable release.

To Reproduce
Steps to reproduce the behavior:

1. Open fre:ac
2. Load a big joblist of flac files
3. Select FLAC encoder with default settings
4. Enable Create cue sheet and Encode to single file
5. Open the Output splitting tool, select Split by metadata
6. Pattern to compare: <albumartist>,<album>,<year>,<disc>
7. Filename pattern: <albumartist>/<year> - <album> CD<disc(2)>
8. Hit convert on the Output splitting tool window
9. The app crashes, sometimes inmediately and sometimes it manages to create some files, maybe depending on the joblist size

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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System (please complete the following information)

• OS: Debian 12 Stable, using Flatpak fre:ac version 1.1.7
• CPU: AMD Ryzen 5 Pro 5650U
• RAM: 16 GB

Additional context
Also tried with the AppImages and on Windows, similar outcome.

[umfuz]

I think it might be an issue of resource handling. If I disable 'Parallel processing', then although slower it runs succesfully on bigger joblists. It will still crash if I add all the files at once, but I managed to get the job done by batches. Given this, I think it could be related to #563.

I guess it wouldn't hurt to mention that I have without issues converted my whole collection to AAC and Opus using fre:ac, so this specific job of merging FLACs seems to trigger the problem more easily.