Cleans up webpack error messages. eslint-disable-next-line no-unused-vars
function formatMessage(message, isError) {
  var lines = message.split('\n');

  if (lines.length > 2 && lines[1] === '') {
    // Remove extra newline.
    lines.splice(1, 1);
  }

  // Remove webpack-specific loader notation from filename.
  // Before:
  // ./~/css-loader!./~/postcss-loader!./src/App.css
  // After:
  // ./src/App.css
  if (lines[0].lastIndexOf('!') !== -1) {
    lines[0] = lines[0].substr(lines[0].lastIndexOf('!') + 1);
  }

  lines = lines.filter(function (line) {
    // Webpack adds a list of entry points to warning messages:
    //  @ ./src/index.js
    //  @ multi react-scripts/~/react-dev-utils/webpackHotDevClient.js ...
    // It is misleading (and unrelated to the warnings) so we clean it up.
    // It is only useful for syntax errors but we have beautiful frames for them.
    return line.indexOf(' @ ') !== 0;
  });

  // line #0 is filename
  // line #1 is the main error message
  if (!lines[0] || !lines[1]) {
    return lines.join('\n');
  }

  // Cleans up verbose "module not found" messages for files and packages.
  if (lines[1].indexOf('Module not found: ') === 0) {
    lines = [lines[0],
    // Clean up message because "Module not found: " is descriptive enough.
    lines[1].replace('Cannot resolve \'file\' or \'directory\' ', '').replace('Cannot resolve module ', '').replace('Error: ', '').replace('[CaseSensitivePathsPlugin] ', '')];
  }

  // Cleans up syntax error messages.
  if (lines[1].indexOf('Module build failed: ') === 0) {
    lines[1] = lines[1].replace('Module build failed: SyntaxError:', friendlySyntaxErrorLabel);
  }

  // Clean up export errors.
  // TODO: we should really send a PR to Webpack for this.
  var exportError = /\s*(.+?)\s*(")?export '(.+?)' was not found in '(.+?)'/;
  if (lines[1].match(exportError)) {
    lines[1] = lines[1].replace(exportError, '$1 \'$4\' does not contain an export named \'$3\'.');
  }

  lines[0] = colors.inverse(lines[0]);

  // Reassemble the message.
  message = lines.map(function (line) {
    if (line.indexOf('vue-template-compiler must be installed as a peer dependency') > -1) {
      return 'You need to install "vue-template-compiler" alongside "vue" in your project.'
    }
    return line
  }).join('\n');
  // Internal stacks are generally useless so we strip them... with the
  // exception of:
  // 1: stacks containing `webpack:` because they're normally
  // from user code generated by WebPack. For more information see
  // https://github.com/facebookincubator/create-react-app/pull/1050
  // 2: from eval-loader
  var isEvalLoaderError = /webpack\/eval-loader\.js/.exec(lines[1])
  if (!isEvalLoaderError) {
    message = message.replace(/^\s*at\s((?!webpack:).)*:\d+:\d+[\s)]*(\n|$)/gm, ''); // at ... ...:x:y
  }

  return message.trim();
}