[BUGFIX] Prevent JS SyntaxError on extension installation

In case an extension should be installed
via the extension manager, containing code
which might stop the PHP request, e.g. the
common "defined('TYPO3_MODE') or die();" check,
the corresponding JS component does no longer
generate a SyntaxError on calling .json()
on the empty response body.

Instead, the error is caught and the integrator
is being informed via a flash message.

Resolves: #102512
Releases: main, 12.4
Change-Id: I4acc6f972be91b137c943edfec51d283e9268426
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81966


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>