Um... yeah, this really is a non-issue as I'm sure corrupted ttf files don't often exist, and also if it did somehow occur, it would surely occur as soon as the program was run, and it's surely not worth adding any complexity just for this. I think I got overenthusiastic to report it when I noticed something crashed. Sorry about that. :D
Actually I discovered this when trying to load something which wasn't a font, then I tried manually removing part of a ttf file and it crashed again, so I don't have any "real world" examples of corrupted fonts.