a lightweight error handler
npm install l-error
###register(type, code)
Parameter:
type(string=)
code(number=)
Example:
Err.register('NOT_FOUND', 404)
###constructor(code, opts_message | type)
Parameter:
code(number=)
opts_message(string=)
type(Err.ErrType)
Example:
new Err(404, 'NOT_FOUND'); | new Err(Err.NOT_FOUND)