GUI: Strange error messages with incorrectly set extras path

[dfsgand]

ScummVM version checked:
ScummVM 2.9.0git5034-g8019d0eea13 (Jun 1 2024 20:18:24)
Using SDL backend with SDL 2.0.14
Features compiled in: Vorbis FLAC MP3 ALSA SEQ sndio TiMidity RGB zLib MikMod VPX A/52 FreeType2 FriBiDi JPEG PNG ENet SDL2 TinyGL OpenGL (with shaders)
Platform: Debian 11.9 bullseye, x86-64

When the extra path is set to a directory missing the files that are usually in dists/engine-data, the ScummVM GUI will revert to a fixed font and attempts to change GUIs or the GUI language give a console error indicating something is wrong with TrueType rendering:

WARNING: Couldn't load font 'helvb12.bdf'/'FreeSansBold.ttf'!

  File <File Stream>, line 150:
<language id = '*'   scalable_file = 'FreeSansBold.ttf'/>
		</font>

Parser error: Error loading localized Font in theme engine.

WARNING: Failed to parse STX file 'remastered_gfx.stx'!
WARNING: Failed to load theme '/home/user/.local/share/scummvm/gui/themes/residualvm.zip'!

I originally bumped into this while adding MT32 control ROMs to a local extras directory without copying the dist/engine-data files over. The TrueType error got me on entirely the wrong path, and I spent a lot of time trying to figure out what was wrong given that the TrueType fonts were visible to the rest of the system.

So this is something between a defect and feature request. That it reports an error reading a font might be a bug or engine-data could be containing the ttf file it's looking for. As a feature request, it would be nice if it would throw a message box saying the extras directory is wrong or missing files required. As a bug, that it instead reports fonts errors seems wrong or at least quite strange.

In addition, when trying to set a different theme language, the GUI will say "Theme does not support selected language!", which seems inaccurate.