Expand custom error usage #106
Description
I think you could get more out of defining your own errors if you want. You could have a default standard message for example and pass the domain variable(s) as input, and only show a custom message if it is specified. Also you could inherit from ValueError instead, as it is a specific case of ValueError. See https://docs.python.org/3/library/exceptions.html#UnicodeError as an example. This might also help you get rid of some duplicate code/strings above.
These are all just minor suggestions, feel free to ignore them for now.
Originally posted by @JaroCamphuijsen in #97 (comment)