pango-1.12.3.zip gtk+-2.8.18.zip
Yep, this stops it dying horribly in the font selector. Instead it just shows a whole row of those 'no glyph' boxes (I'm testing with GeoType TT from bug 1474337).
I've just checked in a fix to stop things crashing when you actually try to render some canvas text with one of the dodgy fonts, but it's still not great. It falls back to Sans for the rasterisation but Pango is still using the extents and character-to-glyph mapping from the real font (which it has failed to read hence are all zeros), so you end up with the wrong characters all on top of each other. But it doesn't crash.
It would be better to detect fonts that aren't going to work earlier so that we can do the entire render with Sans, but that's kind of awkward because we don't know the font that Pango's going to choose until too late. Anyway, this way we get a very visible reminder that it would be nice to fix Pango.
Richard.