Early successes

ERROR: AddressSanitizer: heap-buffer-overflow on address 0x615000000ffa READ of size 2 at 0x615000000ffa thread T0 SCARINESS: 24 (2-byte-read-heap-buffer-overflow-far-from-bounds) #0 0x885e06 in tt_face_vary_cvtsrc/truetype/ttgxvar.c:1556:31

Contributions and feedback are welcome