message: fix logic
diff: @@ -18,6 +18,7 @@ import { Command } from 'commander';
  import { TechdocsGenerator } from '@backstage/plugin-techdocs-node';
  const defaultDockerImage = TechdocsGenerator.defaultDockerImage;
  +const defaultPreviewAppPort = '3000';
  export function registerCommands(program: Command) {
  program
  @@ -258,11 +259,11 @@ export function registerCommands(program: Command) {
  .option(
  '--preview-app-port <PORT>',
  'Port for the preview app to be served on',
  - '3000',
  + defaultPreviewAppPort,
  )
  .hook('preAction', command => {
  if (
  - command.opts().previewAppPort &&
  + command.opts().previewAppPort !== defaultPreviewAppPort &&
  !command.opts().previewAppBundlePath
  ) {
  command.error(
  