Regression: lapce now fails to load any editor fonts, falls back to not-monospace/varied glyph width font

With the recent bigger lapce update, I think the one to the different UI toolkit, it now fails to load any editor fonts. No matter which font name I try, none of them is applied. (It also doesn't even tell me that it failed, but I can see so since I know how the fonts are meant to look like.) However, it also falls back to not-monospace/varied glyph width font for the code which makes this more than a cosmetic problem and actually turns the editor somewhat unusable.

No files, tests, or entry points are named. Reproduce the font selection failure in the Lapce Flatpak, verify that code uses a proportional or varied-width fallback, and identify whether the regression comes from the UI toolkit change; done means configured editor fonts load and the code font is monospace.

Written by the indexing model from the issue text.