bmesh's 'Join Edge Kill Vert' was using own code to delete loops, instead of using `bm_kill_only_loop()`, which did not tag loop indices as dirty (causing the crash), but also did not free loop's CDData...
bmesh's 'Join Edge Kill Vert' was using own code to delete loops, instead of using `bm_kill_only_loop()`, which did not tag loop indices as dirty (causing the crash), but also did not free loop's CDData...