Static and dynamic memory is restricted to below $0ffff (64k).  Past
this mark is high memory.  Frotz previously stored the address for
printing a string in a zword variable (unsigned short).  An unsigned
short is two bytes and therefore loops back to zero after passing
0xffff.  When decode_text() was given a string that straddles the 64k
boundary, the address variable looped back to zero, which then provoked
a segfault.

Per the Z-machine Standard, the proper action to take when crossing that
boundary is undefined.  If the value in the address variable is copied
to a zlong variable (unsigned long) before proceeding, printing one of
these naughty strings will succeed without complaint.  Allowing that to
happen is in direct opposition to why segfaults happen in the first
place: when a program starts writing outside your allocated memory,
that's a clear indication that the program has aquired a faulty picture
of what should be happening. Therefore I have Frotz throw a fatal error
when encountering such a print attempt.