Lot of errors (terminal) while starting the Appimage of MuseScore

Issue type

Other type of issue

Description with steps to reproduce

Download the appimage of MuseScore, open it from the terminal (after chmod +x of course) and you get a big list of errors. Some seem innocent (not being able to connect immediately), some seem more serious like musesampler errors and UI-errors.
I don't know how bad it is and if the developers are aware of this but I will show the output in added screenshots so that the developers might benefit from it. The program seems to be working fine but I am not an advanced user.

Also, apparently xml does not appreciate variable-names being capitalized, see the first screenshot. Could that eventually become a problem?

I noticed this for both 4.4.2 and for 4.3.2. and on both Arch and Ubuntu-base.

Supporting files, videos and screenshots

What is the latest version of MuseScore Studio where this issue is present?

4.4.2

Regression

No.

Operating system

Linux (Arch and popOS)

Additional context

I use this AppImage on both my desktop (Arch) and laptop (popOS), I get the same errors in the terminal, as to be expected because it is an AppImage and those should run the same on every Linux distribution.

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

Start by reproducing the MuseScore AppImage from a terminal on Arch or an Ubuntu-based system, using the screenshots and reported versions as the comparison point. Trace which terminal messages correspond to MuseSampler, UI, connection, and XML behavior; done means the relevant errors are identified and the issue has a reproducible scope and verification criteria.