packages/next/client/dev-error-overlay/format-webpack-messages.js
function formatMessage (message, isError) {
  let lines = message.split('\n')

  // Strip Webpack-added headers off errors/warnings
  // https://github.com/webpack/webpack/blob/master/lib/ModuleError.js
  lines = lines.filter(line => !/Module [A-z ]+\(from/.test(line))

  // Transform parsing error into syntax error
  // TODO: move this to our ESLint formatter?
  lines = lines.map(line => {
    const parsingError = /Line (\d+):(?:(\d+):)?\s*Parsing error: (.+)$/.exec(
      line
    )
    if (!parsingError) {
      return line
    }
    const [, errorLine, errorColumn, errorMessage] = parsingError
    return `${friendlySyntaxErrorLabel} ${errorMessage} (${errorLine}:${errorColumn})`
  })

  message = lines.join('\n')
  // Smoosh syntax errors (commonly found in CSS)
  message = message.replace(
    /SyntaxError\s+\((\d+):(\d+)\)\s*(.+?)\n/g,
    `${friendlySyntaxErrorLabel} $3 ($1:$2)\n`
  )
  // Remove columns from ESLint formatter output (we added these for more
  // accurate syntax errors)
  message = message.replace(/Line (\d+):\d+:/g, 'Line $1:')
  // Clean up export errors
  message = message.replace(
    /^.*export '(.+?)' was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$1' is not exported from '$2'.`
  )
  message = message.replace(
    /^.*export 'default' \(imported as '(.+?)'\) was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$2' does not contain a default export (imported as '$1').`
  )
  message = message.replace(
    /^.*export '(.+?)' \(imported as '(.+?)'\) was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$1' is not exported from '$3' (imported as '$2').`
  )
  lines = message.split('\n')

  // Remove leading newline
  if (lines.length > 2 && lines[1].trim() === '') {
    lines.splice(1, 1)
  }
  // Clean up file name
  lines[0] = lines[0].replace(/^(.*) \d+:\d+-\d+$/, '$1')

  // Cleans up verbose "module not found" messages for files and packages.
  if (lines[1] && lines[1].indexOf('Module not found: ') === 0) {
    lines = [
      lines[0],
      lines[1]
        .replace('Error: ', '')
        .replace('Module not found: Cannot find file:', 'Cannot find file:')
    ]
  }

  message = lines.join('\n')
  // Internal stacks are generally useless so we strip them... with the
  // exception of stacks containing `webpack:` because they're normally
  // from user code generated by Webpack. For more information see
  // https://github.com/facebook/create-react-app/pull/1050
  message = message.replace(
    /^\s*at\s((?!webpack:).)*:\d+:\d+[\s)]*(\n|$)/gm,
    ''
  ) // at ... ...:x:y
  message = message.replace(/^\s*at\s<anonymous>(\n|$)/gm, '') // at <anonymous>
  lines = message.split('\n')

  // Remove duplicated newlines
  lines = lines.filter(
    (line, index, arr) =>
      index === 0 || line.trim() !== '' || line.trim() !== arr[index - 1].trim()
  )

  // Reassemble the message
  message = lines.join('\n')
  return message.trim()
}
function formatMessage (message, isError) {
  let lines = message.split('\n')

  // Strip Webpack-added headers off errors/warnings
  // https://github.com/webpack/webpack/blob/master/lib/ModuleError.js
  lines = lines.filter(line => !/Module [A-z ]+\(from/.test(line))

  // Transform parsing error into syntax error
  // TODO: move this to our ESLint formatter?
  lines = lines.map(line => {
    const parsingError = /Line (\d+):(?:(\d+):)?\s*Parsing error: (.+)$/.exec(
      line
    )
    if (!parsingError) {
      return line
    }
    const [, errorLine, errorColumn, errorMessage] = parsingError
    return `${friendlySyntaxErrorLabel} ${errorMessage} (${errorLine}:${errorColumn})`
  })

  message = lines.join('\n')
  // Smoosh syntax errors (commonly found in CSS)
  message = message.replace(
    /SyntaxError\s+\((\d+):(\d+)\)\s*(.+?)\n/g,
    `${friendlySyntaxErrorLabel} $3 ($1:$2)\n`
  )
  // Remove columns from ESLint formatter output (we added these for more
  // accurate syntax errors)
  message = message.replace(/Line (\d+):\d+:/g, 'Line $1:')
  // Clean up export errors
  message = message.replace(
    /^.*export '(.+?)' was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$1' is not exported from '$2'.`
  )
  message = message.replace(
    /^.*export 'default' \(imported as '(.+?)'\) was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$2' does not contain a default export (imported as '$1').`
  )
  message = message.replace(
    /^.*export '(.+?)' \(imported as '(.+?)'\) was not found in '(.+?)'.*$/gm,
    `Attempted import error: '$1' is not exported from '$3' (imported as '$2').`
  )
  lines = message.split('\n')

  // Remove leading newline
  if (lines.length > 2 && lines[1].trim() === '') {
    lines.splice(1, 1)
  }
  // Clean up file name
  lines[0] = lines[0].replace(/^(.*) \d+:\d+-\d+$/, '$1')

  // Cleans up verbose "module not found" messages for files and packages.
  if (lines[1] && lines[1].indexOf('Module not found: ') === 0) {
    lines = [
      lines[0],
      lines[1]
        .replace('Error: ', '')
        .replace('Module not found: Cannot find file:', 'Cannot find file:')
    ]
  }

  message = lines.join('\n')
  // Internal stacks are generally useless so we strip them... with the
  // exception of stacks containing `webpack:` because they're normally
  // from user code generated by Webpack. For more information see
  // https://github.com/facebook/create-react-app/pull/1050
  message = message.replace(
    /^\s*at\s((?!webpack:).)*:\d+:\d+[\s)]*(\n|$)/gm,
    ''
  ) // at ... ...:x:y
  message = message.replace(/^\s*at\s<anonymous>(\n|$)/gm, '') // at <anonymous>
  lines = message.split('\n')

  // Remove duplicated newlines
  lines = lines.filter(
    (line, index, arr) =>
      index === 0 || line.trim() !== '' || line.trim() !== arr[index - 1].trim()
  )

  // Reassemble the message
  message = lines.join('\n')
  return message.trim()
}
Cleans up webpack error messages. eslint-disable-next-line no-unused-vars