🚀 go-pugleaf

This is surely not a bug, but it's a confusing error message which I can't
find documented. It has to do with TeX-buffer and related commands.
'doctor' does not help.

Any hints will be appreciated. Thanks, Phil Nelson 
                                       nelson@mohlsun.physics.upenn.edu


I run emacs -q file.tex
(Any TeX file has this problem.) (Or visit a new file and put any TeX input
in the buffer.)

I immediately say M-x TeX-buffer
Here is debug output:
Signalling: (wrong-type-argument stringp nil)
  start-process("TeX-shell" #<buffer *TeX-shell*> "/usr/local/tools/gnu-emacs-1851/etc/env" "TERMCAP=emacs:co#80:tc=unknown:" "TERM=emacs" "EMACS=t" "-" nil "-v")
  apply(start-process "TeX-shell" #<buffer *TeX-shell*> "/usr/local/tools/gnu-emacs-1851/etc/env" "TERMCAP=emacs:co#80:tc=unknown:" "TERM=emacs" "EMACS=t" "-" nil "-v")
  byte-code("JK	KQ!EEEL!	\n
  make-shell("TeX-shell" nil nostartfile "-v")
  byte-code("CD!
  TeX-start-shell()
  byte-code("LST!
  TeX-region(1 14378)
  byte-code("@Aed\"" [nil TeX-region] 3)
  TeX-buffer()
  call-interactively(TeX-buffer)
  execute-extended-command(nil)
* call-interactively(execute-extended-command)


=======================================================================
The second try in one session is different. Now the debug output is:
Signalling: (error "Process TeX-shell does not exist")
  quit-process("TeX-shell" t)
  byte-code("ABC@\"" [t nil quit-process "TeX-shell"] 3)
  TeX-kill-job()
  byte-code("LST!
  TeX-region(1 14378)
  byte-code("@Aed\"" [nil TeX-region] 3)
  TeX-buffer()
  call-interactively(TeX-buffer)
  execute-extended-command(nil)
* call-interactively(execute-extended-command)