added mechanism for undetected/uncategorized errors

[suchAdemon]

• as well added first errror for result code 13 for better visibility
• also added full path for sed binaries to avoide alias are getting used, same goes for grep

[aswen]

Nice, I've got one question about:

also added full path for sed binaries to avoide alias are getting used, same goes for grep

Did you verify that the path of those programs is the same on all possible systems where this script is being used? (particularly FreeBSD)