So I was cruising along with my chaingun, shooting some guys, nailed a barrel and BLAM:
$0046BB40 TLEVEL__VISIBLE, line 434 of dflevel.pas
$0046726F TBEING__SENDMISSILE, line 1292 of dfbeing.pas
$00462108 TBEING__FIRE, line 537 of dfbeing.pas
$00450CDD TPLAYER__DOFIRE, line 685 of dfplayer.pas
$004523BB TPLAYER__AICONTROL, line 953 of dfplayer.pas
$00463E7C TBEING__ACTION, line 776 of dfbeing.pas
$00463FE7 TBEING__CALL, line 789 of dfbeing.pas
$0046E32D TLEVEL__TICK, line 782 of dflevel.pas
$0040F30A TDOOM__RUN, line 275 of doombase.pas
$004019A0 main, line 22 of doomrl.pas
Fortunately it was able to save *pshew*. Back to mowing down zombies.