code: func (p *parser) error(err error) {
  	perr := &ParseErr{
  		Line: p.lex.lineNumber(),
  		Pos:  p.lex.linePosition(),
  		Err:  err,
  	}
  	if strings.Count(strings.TrimSpace(p.lex.input), "\n") == 0 {
  		perr.Line = 0
  	}
  	panic(perr)
  }
docs: // error terminates processing.