Benjamin Franzke authored Dec 10, 2020 and Christian Kuhn committed Jan 06, 2021

 * Fix 500 vs 503 error for configuration vs maintenance errors
 * Fix maintenance mode middleware ordering to get access to site
   related error handlers
 * Fix ErrorController unit tests to actually test
   for 503 and 500 error responses (contained duplicate
   code that didn't actually test for the non-configured
   state, but the devIPMask state)

For 5xx status code we have two different cases right now:
 * configuration errors, which need to respond with 500
 * maintenance mode, which is a 503 response

Therefore TSFE now uses internalErrorAction()
to respond with "500 Internal Server Error" when
the page configuration is broken.

Resolves: #93045
Related: #93032
Releases: master, 10.4
Change-Id: I60de9f7ba06d17f2e6e5c8f20c9fc10e90b4175b
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67080

Tested-by: Martin Kutschker <mkutschker-typo3@yahoo.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Martin Kutschker <mkutschker-typo3@yahoo.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>