Handle different error types #39

Currently, all error types seem to be represented as new Error(<message>). Other error types like SyntaxError, ReferenceError etc, are not serialized any differently

Suggestion:

stringify(new SyntaxError('syntax')); // "new SyntaxError(syntax')"
stringify(new ReferenceError('syntax')); // "new ReferenceError(syntax')"
...

It should be possible to do this using Error.prototype.name with the caveat that it can be overridden to an empty string, which should probably be handled