Check result sprite group of RoadStopResolverObject in DrawTile_Station

src/station_cmd.cpp

@@ -3547,10 +3547,12 @@ draw_default_foundation:
 			st = BaseStation::GetByTile(ti->tile);
 			RoadStopResolverObject object(stopspec, st, ti->tile, INVALID_ROADTYPE, type, view);
 			const SpriteGroup *group = object.Resolve();
-			const DrawTileSprites *dts = ((const TileLayoutSpriteGroup *)group)->ProcessRegisters(nullptr);
-			t = dts;
-			if (type == STATION_ROADWAYPOINT && (stopspec->draw_mode & ROADSTOP_DRAW_MODE_WAYP_GROUND)) {
-				draw_ground = true;
+			if (group != nullptr && group->type == SGT_TILELAYOUT) {
+				const DrawTileSprites *dts = ((const TileLayoutSpriteGroup *)group)->ProcessRegisters(nullptr);
+				t = dts;
+				if (type == STATION_ROADWAYPOINT && (stopspec->draw_mode & ROADSTOP_DRAW_MODE_WAYP_GROUND)) {
+					draw_ground = true;
+				}
 			}
 		}