Where do I find a list of error codes?

I’m trying to interpret various error codes from a system scan, but cannot find them documented anywhere.

Most of them appear to be bugs in Avast – unable to interpret certain compressed file formats correctly for example.

Hi,
there’s no such a list. You can refer to Application string resources (/Applications/avast!.app/Contents/Resources/English.lproj/Error.strings)

Best Regards,
Martin