Can't raise a string
Use dedicated str methods' arguments instead of creating a slice
Simplify column number calculation by removing special-casing
(since str.[r]find returns -1 when the substring is not found)
Don't fail while trying to report an error if stream is not a string
Remove 'parse error:' from error message since it's going to be displayed as the class name anyway
Merge pull request #3 from bugaevc/error_reporting

Error reporting fixes