Fix #9527: Crash when trying to place multitile objects at map edge

src/object_cmd.cpp

@@ -220,6 +220,9 @@ CommandCost CmdBuildObject(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 	int size_x = GB(spec->size, HasBit(view, 0) ? 4 : 0, 4);
 	int size_y = GB(spec->size, HasBit(view, 0) ? 0 : 4, 4);
 	TileArea ta(tile, size_x, size_y);
+	for (TileIndex t : ta) {
+		if (!IsValidTile(t)) return_cmd_error(STR_ERROR_TOO_CLOSE_TO_EDGE_OF_MAP_SUB); // Might be off the map
+	}
 
 	if (type == OBJECT_OWNED_LAND) {
 		/* Owned land is special as it can be placed on any slope. */