fix(specialpower): Prevent null pointer dereference in Thing::setPosition

[seer-by-sentry]

This PR addresses issue CLIENT-520, a fatal crash caused by a null pointer dereference in Thing::setPosition.

Root Cause:
SpecialPowerModule::doSpecialPowerUsingWaypoints intentionally calls triggerSpecialPower(nullptr) for special powers that do not create view objects. This nullptr is then forwarded to SpecialPowerModule::createViewObject. The createViewObject function, however, did not have an early null check for the location parameter. Consequently, after creating a viewObject, it would attempt to call viewObject->setPosition(location) with a null location, leading to an EXCEPTION_ACCESS_VIOLATION_READ.

Solution:
Added an if (location == nullptr) return; guard at the very beginning of SpecialPowerModule::createViewObject in both Generals/ and GeneralsMD/ code paths. This ensures that if a special power does not require a view object (and thus passes a null location), the function exits gracefully without attempting to set the position of a non-existent object at a null location.

Fixes CLIENT-520