code: function tryFile(requestPath, isMain) {
          const rc = stat(requestPath);
          if (preserveSymlinks && !isMain) {
              return rc === 0 && path.resolve(requestPath);
          }
          return rc === 0 && fs.realpathSync(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.