Compatibility with older files was just broken by the new version

[thelabcat]

Describe the bug
When I try to open existing files from the previous version of MusE (that is, from 4.1), the program crashes (after loading plugins and giving an audio samplerate warning).

To Reproduce
Steps to reproduce the behavior:

1. Open MusE.
2. Attempt to open a file created before the current version (4.2).
3. After some common loading dialogs, the program will crash.

Expected behavior
I can still open my old project files, or at the very least get a proper error message that they are incompatible with the current version.

Desktop (please complete the following information):

• OS: Fedora 38
• Desktop: KDE Plasma

Additional context
I am using the FlatHub version of MusE. Notably, the FlatHub version number is incorrect; inconsistent with the splash.
MusE is still able to save new files and then re-open them in the current version.
I have tried altering audio server settings.

[thelabcat]

Additional info: The templates were apparently not re-created for the new version, and so loading a factory template also causes a crash.

[spamatica]

I can't reproduce this behaviour with my own built version or with the AppImage.
I'm not versed in Flathub so can't say if or how it can interfere, the wrong version number is a hint though.. Maybe it's not actually 4.2 but built from the master at a point where there was a breaking bug?
At flathub.org I only see 4.1 listed.

[thelabcat]

I can't reproduce this behaviour with my own built version or with the AppImage. I'm not versed in Flathub so can't say if or how it can interfere, the wrong version number is a hint though.. Maybe it's not actually 4.2 but built from the master at a point where there was a breaking bug? At flathub.org I only see 4.1 listed.

Confirmed, it is the flatpak.