statement in file "io.d", line 5484 has been reached!!

[<don...@is...>]

(I hope that sending clisp-devel will be less likely to put my
address on spam lists than clisp-list.)

====
EVAL frame for form (LIST :ARDA-FORM :ERROR (FORMAT NIL "~a" ERR))
1. Break AP5[8]> (princ err)
Non-existent directive
Current point in control string:
  <INPUT name="change-views" type="submit" ~ 

*** - internal error: statement in file "io.d", line 5484 has been reached!!
Please send the authors of the program a description how you produced this error!
====

This comes from my build from some time after 2.31, ~10/2003 when I
was adding nohang to read/write byte sequence stuff.
That change appears not to have affected io.d, however.
The io.d that I have (and I'm pretty confident is the one from which
this image was built) contains this, ending at line 5484:
====
local uintL format_tab (object stream, object colon_p, object atsig_p,
                        object col_num, object col_inc) {
  var uintL col_num_i;
  if (nullp(col_num)) col_num_i = 1;
  else if (posfixnump(col_num)) col_num_i = posfixnum_to_L(col_num);
  else NOTREACHED; # fehler_posfixnum(col_num);
  var uintL col_inc_i;
  if (nullp(col_inc)) col_inc_i = 1;
  else if (posfixnump(col_inc)) col_inc_i = posfixnum_to_L(col_inc);
  else NOTREACHED; # fehler_posfixnum(col_inc);
====

The problem is related to a tilde followed by a space followed by a
newline (which of course was my mistake).
I don't know how to reproduce it from a clean image, but the image
in which it appeared is still running, and I can reproduce the error
there.  Let me know what experiments would be useful in that image.