packages/next/client/dev-error-overlay/hot-dev-client.js
function handleErrors (errors) {
  clearOutdatedErrors()

  isFirstCompilation = false
  hasCompileErrors = true

  // "Massage" webpack messages.
  var formatted = formatWebpackMessages({
    errors: errors,
    warnings: []
  })

  // Only show the first error.
  ErrorOverlay.reportBuildError(formatted.errors[0])

  // Also log them to the console.
  if (typeof console !== 'undefined' && typeof console.error === 'function') {
    for (var i = 0; i < formatted.errors.length; i++) {
      console.error(stripAnsi(formatted.errors[i]))
    }
  }
}
function handleErrors (errors) {
  clearOutdatedErrors()

  isFirstCompilation = false
  hasCompileErrors = true

  // "Massage" webpack messages.
  var formatted = formatWebpackMessages({
    errors: errors,
    warnings: []
  })

  // Only show the first error.
  ErrorOverlay.reportBuildError(formatted.errors[0])

  // Also log them to the console.
  if (typeof console !== 'undefined' && typeof console.error === 'function') {
    for (var i = 0; i < formatted.errors.length; i++) {
      console.error(stripAnsi(formatted.errors[i]))
    }
  }
}
Compilation with errors (e.g. syntax error or missing modules).