Implement lexer option "prohibit_raiseonerror_filter". Sphinx raises by default when an Error token is seen (by means of the "raiseonerror" filter that is applied by default to lexers in Sphinx). This option skips this and allows error locations to be seen and highlighted properly. While there convert most Generic.Error tokens to Error tokens because now they can be handled by a lexer with "prohibit_raiseonerror_filter=True".