This is a simple implementation of an error printer that highlights the
error location with squiggly lines, for example:
File "dune", line 1, characters 14-21:
(copy_files %{read:x}/*)
^^^^^^
The message is not displayed in some cases, like if the file does not
exist, or if the location spans multiple lines.
Signed-off-by: Etienne Millon <me@emillon.org>
06bc3b1d0c