slash-error.sql expects its only parameter to be the path of a script (file) to a
PL/SQL object (package, package body, …)
without a trailing slash. The script the reads the content of the file (
@…) and then adds a slash so that the object gets compiled and then also executes
show errors.
This script was once necessary because I worked in an environment where the rule was that slashes and/or show errors statements were prohibited in the source code repository, but I wanted to have a one liner that installed a PL/SQL object and showed errors (if any).