Fix plKeyImp warning about comparison of this and nullptr.

Sources/Plasma/NucleusLib/pnKeyedObject/plKeyImp.cpp

@@ -74,6 +74,10 @@ bool IsTrackedKey(const plKeyImp* key)
 }
 #endif
 
+hsKeyedObject* plKeyImp::SafeGetObject(const plKeyImp* key) {
+    return key ? key->fObjectPtr : nullptr;
+}
+
 plKeyImp::plKeyImp() :
     fObjectPtr(nil),
     fStartPos(-1),
@@ -156,7 +160,7 @@ hsKeyedObject* plKeyImp::GetObjectPtr()
 
 hsKeyedObject* plKeyImp::ObjectIsLoaded() const
 {
-    return this ? fObjectPtr : nil;
+    return plKeyImp::SafeGetObject(this);
 }
 
 // Copy the contents of p for cloning process

Sources/Plasma/NucleusLib/pnKeyedObject/plKeyImp.h

@@ -53,6 +53,9 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 //------------------------------------
 class plKeyImp : public plKeyData 
 {
+private:
+    static hsKeyedObject* SafeGetObject(const plKeyImp* key);
+
 public:
     plKeyImp();
     plKeyImp(plUoid, uint32_t pos,uint32_t len);