Turns out this is an ABI break in lp:fontconfig, and after fixing that theres an ABI break in lp:pango, compiling both those from source has fixed the crash (after running it more then 1000 times).
Turns out this is an ABI break in lp:fontconfig, and after fixing that theres an ABI break in lp:pango, compiling both those from source has fixed the crash (after running it more then 1000 times).