Check if version entity is not null before delete

[solracsf]

• Resolves: [Bug]: TypeError: OCP\AppFramework\Db\QBMapper::delete(): Argument #1 ($entity) must be of type OCP\AppFramework\Db\Entity, null given #37407

Summary

Check if version entity is not null before delete. This variable is being set in the array_filter() function, but it is possible that it remains empty if the function doesn't find any version that matches the conditions.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[solracsf]

/backport to stable26

[artonge]

🙈