showFile(filePath, error) {
    const lines = fs.readFileSync(filePath).toString().split('\n');
    const start = Math.max(error.loc.line - 3, 1);
    const end = Math.min(error.loc.line + 3, lines.length);
    const targetLines = [];
    for (let i = start - 1; i < end; i++) {
      targetLines.push(`${i + 1}| ${lines[i]}`);
    }

    console.log('[31mwarning: could not parse the following code. if you want to use ECMAScript proposals, see https://esdoc.org/manual/feature.html#ecmascript-proposal[32m');
    console.log(filePath);
    console.log(`${targetLines.join('\n')}[0m`);

    this._logs.push({filePath: filePath, log: [start, end]});
  }
show log.
@param {string} filePath - invalid code in this file.
@param {Error} error - error object.