Check if errors occured during a latex run by
        scanning the output.

def check_errors(self):
        '''
        Check if errors occured during a latex run by
        scanning the output.
        '''
        errors = ERROR_PATTTERN.findall(self.out)
        # "errors" is a list of tuples
        if errors:
            self.log.error('! Errors occurred:')

            self.log.error('\n'.join(
                [error.replace('\r', '').strip() for error
                 in chain(*errors) if error.strip()]
            ))

            self.log.error('! See "%s.log" for details.' % self.project_name)

            if self.opt.exit_on_error:
                self.log.error('! Exiting...')
                sys.exit(1)