Emacs crashes with video invoked when requested Emacs line length exceeds Multics video line length.

[Jeffrey H. Johnson <trnsz@…>]

1. stty -ttp vt102
2. wdc invoke
3. emacs -ll 104 >udd>Ring0>JJohnson>speed>instr_speed.pl1
4. Hold down Control-N (scrollng down line by line).

Once it scrolls to the line containing the ^{L character, Emacs will crash:}

Error:  emacs error by e_pl1_$signal_io_error|14573
(>system_library_unbundled>bound_multics_emacs_)
The request was not within the boundaries of the requesting window. Emacs encou
\cntered an error. Error from window_$<<video system ctl>>.
Give the following command:
file_output emacs_trace_;trace_stack;revert_output
and save the results for programming staff.

This happens when using Multics video system with a terminal of 80 width, but (likely erroneously) specifying that Emacs should use a width of 104.

I encountered this because I had (unintentionally) set an abbrev for emacs which was invoking it with -ll 104, and I was using the 80x25 vt102 terminal.

This is a very abnormal configuration for me, since I normally use a 132x50 terminal.

Rather than crash, if this is truly a fatal configuration error, Emacs should instead just complain that the requested line length exceeds maximum width width of the currently invoked Multics video session.