Fix: Crash when attempting to load old save game with GRFs set

GroupStatistics pool was not initialised before trying to delete vehicles (specifically, trams with no tram track)

(cherry picked from commit 9da1c5bb0b)

src/saveload/afterload.cpp

@@ -2095,6 +2095,7 @@ bool AfterLoadGame()
 	}
 
 	if (IsSavegameVersionBefore(SLV_62)) {
+		GroupStatistics::UpdateAfterLoad(); // Ensure statistics pool is initialised before trying to delete vehicles
 		/* Remove all trams from savegames without tram support.
 		 * There would be trams without tram track under causing crashes sooner or later. */
 		RoadVehicle *v;