Ar an tríú lá is fiche de mí na Nollaig, scríobh Michael Sperber: 

 > Aidan Kehoe <kehoea@parhasard.net> writes:
 > 
 > >  Ar an fichiú lá de mí na Nollaig, scríobh Thomas Mittelstaedt: 
 > >
 > >  > tmstaedt@buildhp3$
 > >  > Fatal error: assertion failed, file window.c, line 2466, RECORD_TYPEP 
 > >  > (obj, lrecord_type_window)
 > >  > WARNING: Unable to auto-save your files properly.
 > >  > Some or all may in fact have been auto-saved.
 > >  > [...]
 > >  > 
 > >  > (gdb) bt
 > >  > #0  0xc01ffd40 in kill () from /usr/lib/libc.2
 > >  > #1  0x000dfcf0 in fatal_error_signal (sig=11) at emacs.c:3800
 > >  > #2  <signal handler called>
 > >  > #3  0x00312e28 in Fnext_window (window=1768846945, minibuf=1074144988, 
 > >  > which_frames=1074063364,
 > >  >     which_devices=1074063364) at window.c:2499
 > >
 > > This is the first “if” test here:
 > >
 > >       while (1)
 > > 	{
 > > 	  if (!NILP (XWINDOW (window)->hchild))
 > > 	    window = XWINDOW (window)->hchild;
 > > 	  else if (!NILP (XWINDOW (window)->vchild))
 > > 	    window = XWINDOW (window)->vchild;
 > > 	  else break;
 > > 	}
 > >
 > > So ‘window’ is something that isn’t a window. Mike, you had lots to do with
 > > the window code when rewriting the window configuration stuff in Lisp; do
 > > you have any idea what provoked this? 
 > 
 > That was mostly above that level, however, so I don't think I can
 > provide specific help.  However, doesn't the Lisp backtrace indicate
 > that the window is nil?

Right, it does, but that’s special-cased at the start of the function and is
replaced by the selected window. 

 > Lisp backtrace follows:
 > 
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  # (unwind-protect ...)
 >  next-window(nil)