The error on quitting the macOS version of the Veil Qt wallet (this time using branch convert-gui-png, but built before the "faq crash fixed") has changed.

$ ./veil-qt -testnet
veil-qt(92912,0x7fff9ff02380) malloc: *** error for object 0x7fc072c04150: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6