message: It seems sometimes it can be unset?
  I have no idea why it works different ways in different places, but this seems safe.
diff: @@ -62,7 +62,7 @@ export default function getOptions({ argv, env, flags, log, packageJson }: Conte
  exitOnceUploaded: trueIfSet(flags.exitOnceUploaded),
  ignoreLastBuildOnBranch: flags.ignoreLastBuildOnBranch,
  // deprecated
  - preserveMissingSpecs: flags.preserveMissing || !!flags.only || flags.onlyStoryNames.length > 0,
  + preserveMissingSpecs: flags.preserveMissing || !!flags.only || !!flags.onlyStoryNames?.length,
  originalArgv: argv,
  buildScriptName: flags.buildScriptName,
  