Add web application error messages

[johnsaigle]

à la this file in SecLists: https://github.com/danielmiessler/SecLists/blob/master/Pattern-Matching/errors.txt

Most of this repo is intended to be used in white-box source code analysis but a list of error messages like this would be a useful thing to import into Burp, for example. You could load this up and have Burp flag HTTP responses containing these strings.

Note that the list above is several years old and most of the errors seem to be related to .NET and PHP. It could be good to extend this to other technologies like Express, Go, and weird Java tech like Tomcat