bugfix(collision): Prevent null dereference in PartitionManager

[seer-by-sentry]

Fixes CLIENT-45T. The issue was that: Object destruction during collision processing leaves dangling pointers in the contact list, causing a use-after-free in Thing::isKindOf.

• Added null checks for 'thisObj' and 'thatObj' in collision detection logic within PartitionManager.cpp.
• Prevents potential null pointer dereferences if one or both objects involved in a collision check have been destroyed or unregistered.

This fix was generated by Seer in Sentry, triggered automatically. 👁️ Run ID: 12411119

Not quite right? Click here to continue debugging with Seer.