[Crash] Unchecked this.userData.ownedItemIds.includes in item validation

[coderabbitai]

Summary

Game server crashes when this.userData.ownedItemIds is undefined during item check.

Affected Code

server-game/src/client.js:468

&& this.userData.ownedItemIds.includes(item.id) // CRASH if ownedItemIds is undefined

Vulnerability

If userData load fails or is incomplete.

Impact

• Game server crash during item validation
• Denial of service

Recommended Fix

&& this.userData?.ownedItemIds?.includes(item.id)

References

• PR: New Blocks & Ported fancyMuzzle flash #43