Error: Stack underflow short.

[I Must Be Crazy 2]

It looks like I've discovered what is causing the procedure timed_event_p_proc in my zivrtrnk.ssl script to not execute at all as soon as the vertibird lands in a new location.

Here's an excerpt from the debug.log file that I took:

ziVrTrnk: Touchdown 12
ZiVrTrnk: On foot at 12
Error during execution:
Stack underflow short.
Current script: scripts\zivrtrnk.int, procedure map_enter_p_proc
FCGUNMER: swap_obj: 1256587672
trunk: map_update_p_proc

The first two lines represent debugging code that I added that indicates that the vertibird had just landed in San Francisco (town reference number 12 in cesaer.int, the script for all the Vertibird dialogs). The two lines in bold worry me; I suspect that this error causes the timed_event_p_proc to not execute, at least not until my player character runs off the current map, then re-enters it again. (I was hoping that solving the 'car disappearing after finding the Vertibird' problem by assigning a different global variable as the Vertibird's placement variable would fix this, but... oh well, at least one annoying bug is out of the way)

This leaves me with three questions:

1. What does stack underflow short mean?
2. Is there a command that I can script using NOID's compiler or Watcom 11.0c that can correct this error (supposedly by freeing up memory or fiddling with the stack)?
3. Is there a utility that I can use to convert *.ssl files produced by NOID's compiler into code readable by Watcom 11.0c?

 

[jargo]

1. What does stack underflow short mean?

Well it mean that you have a call in your script in map_enter_p_proc to not existing object.
In most situation it is an old object pointer (for example pointer to destroyed critter etc).

something like that

variable pilot; 
pilot := self_obj; 
kill_critter (pilot); 
float_msg(pilot,"bal bla me dead",FLOAT_MSG_RED)

It's just a example it will not work.

Is there a utility that I can use to convert *.ssl files produced by NOID's compiler into code readable by Watcom 11.0c?

Yup. Fallout Script Eeditor has NOID -> Interply converter