[BUGFIX] Prevent Uncaught TypeError in ClickMenu.js

This patch prevent an Uncaught TypeError ClickMenu.js.
In case the reloadFrame parameter not exist, the variable res is null.
This is ok, because not in any case the parameter is set.

Resolves: #78329
Releases: master, 7.6
Change-Id: I8590a37c55ed794d62620af4c487b57a972761f7
Reviewed-on: https://review.typo3.org/50259


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Tested-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>