TASK: Fusion Behat Test Make Sure To Throw Runtime Exceptions

[mhsdesign]

Additional fix for #4686

Instead of manually declaring @exceptionHandler we set it automatically for the entry point ;) This will help us detect exceptions which would otherwise be absorbed.

Dont worry, this is only temporary and not at all needed with neos 9

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Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions