UI: Fix uninitialized memory access in OBSPropertiesView

Bug introduced in b0528e0cf7c67d4ae17967bd50fbebb919006f4f. Closes
https://github.com/obsproject/obs-studio/issues/5934.

UI/properties-view.hpp

@@ -98,7 +98,7 @@ private:
 	properties_t properties;
 	OBSData settings;
 	OBSWeakObjectAutoRelease weakObj;
-	void *rawObj;
+	void *rawObj = nullptr;
 	std::string type;
 	PropertiesReloadCallback reloadCallback;
 	PropertiesUpdateCallback callback = nullptr;