[TASK] Extend CustomRequestHandler with a extra condition\

The CustomRequestHandler catches all exceptions and call pageNotFoundAndExit method.
The patch extends now the condition with an extra check for the debug mode and
throw the exception if the debug mode is enabled.

Resolves: #50671

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/df_tools/trunk@78810 735d13b6-9817-0410-8766-e36946ffe9aa