How can the error log be searched?

Greetings!

A customer reported an error generated by our database. However, many
of our functions have errors in RAISE EXCEPTION statements, in which the
% character was omitted. The error message the customer saw was
complaining that there were too many arguments to a RAISE statement. We
were able to find the function that was throwing the error by using
PGAdmin, opening the Server Status window, going to the Log File tab,
and finding approximately when the error occurred.

But it would have been easier to find the problem if we could have
searched the logs. There's no search function in the log file window.
Also, there's no apparent way to export the file. Also, I can't even
use copy and paste. So, how can I export the error messages into a
searchable text file?

Thanks very much!

RobR