bitsy doesn't gracefully handle missing fonts

[le-doux]

currently fails mysteriously if not using the default font and the required font is missing, which is causing problems for Borksy users who accidentally copy over the game data without the font data

suggestion: use default font as fallback

thought: stop hiding the font data?

[le-doux]

ok I fixed the issuer where missing fonts don't cause invalid character boxes to render, but I'm leaving this open for now in case I decide to do something about the underlying issue (the fact that the font data is always available in the textarea)

[le-doux]

closing since I think showing the invalid character boxes is a good enough fix