emacs --debug-init help needed

[Stephen Eglen]

Thanks to Robin for reporting the following problem:

 > I'm having problems with emacs reporting an init file error.
 > After unpacking ess-5.21.tar.gz with tar -xvzf 
 > (and not touching anything inside it),
 > 
 > emacs --debug-init gives the following error message:
 > 
 > >Debugger entered--Lisp error: 
 > >(wrong-type-argument symbolp (&optional 
 > >start-args))
 > >   (defun (&optional start-args) "Call , i.e., 
 > >the R version '' using ESS.\nThis function was 
 > >generated by `ess-r-versions-create'." 
 > >(interactive "P") (let (...) (R start-args)))
...

This error occured because the code that searches for other versions
of R found "R-1.9.1" which in this case was not an executable of R,
but a directory.  Since it it a directory, it had executable bit set
and so ESS assumed it was another version of R to add to the menubar,
causing problems [it wanted to use the name "" in the menubar after
stripping off the directory].

If others get this problem, the work-around is to remove such
directories from your PATH or rename them.  The next version of ESS
should have a fix for this problem.

Stephen