bug#13994: End of buffer error for forward-sexp

[Juri Linkov]

> I would like C-M-f (`forward-sexp') to signal an error when reaching
> the beginning or end of a buffer.

If you want only `C-M-f' to signal an error, then you could create
a new command with a name like `forward-sexp-command' that signals
an error and bind it to `C-M-f'.  That's what e.g `scroll-up-command'
does to control error-signaling only for the command bound to `C-v'
without affecting the lower-level function `scroll-up'.