code: function tryFile(requestPath, isMain) {
    const rc = stat(requestPath);
    if (preserveSymlinks && !isMain) {
      return rc === 0 && path.resolve(requestPath);
    }
    return rc === 0 && toRealPath(requestPath);
  }
docs: check if the file exists and is not a directory if using --preserve-symlinks and isMain is false, keep symlinks intact, otherwise resolve to the absolute realpath.