fix(route_handler): dereference to null cause avoidance module crash (a…

…utowarefoundation#1098)

This crash will not appear unless drivable area boundary is added.

Signed-off-by: Muhammad Zulfaqar Azmi <zulfaqar.azmi@tier4.jp>

planning/route_handler/src/route_handler.cpp

@@ -938,6 +938,9 @@ lanelet::ConstLanelets RouteHandler::getAllLeftSharedLinestringLanelets(
   while (lanelet_at_left) {
     linestring_shared.push_back(lanelet_at_left.get());
     lanelet_at_left = getLeftLanelet(lanelet_at_left.get());
+    if (!lanelet_at_left) {
+      break;
+    }
     lanelet_at_left_opposite = getLeftOppositeLanelets(lanelet_at_left.get());
   }
 
@@ -961,6 +964,9 @@ lanelet::ConstLanelets RouteHandler::getAllRightSharedLinestringLanelets(
   while (lanelet_at_right) {
     linestring_shared.push_back(lanelet_at_right.get());
     lanelet_at_right = getRightLanelet(lanelet_at_right.get());
+    if (!lanelet_at_right) {
+      break;
+    }
     lanelet_at_right_opposite = getRightOppositeLanelets(lanelet_at_right.get());
   }