fix(autoware_utils_geometry): add optional check (#89)

fix(autoware_utils_geometry): add optional check before accessing value in triangulate

Add a check for empty optional before calling .value() on alt_poly.
If alt::Polygon2d::create() returns std::nullopt (e.g., for polygons
with less than 4 points), the function now returns an empty vector
instead of throwing std::bad_optional_access.

Detected by Facebook Infer static analyzer (OPTIONAL_EMPTY_ACCESS).

Signed-off-by: Ryuta Kambe <ryuta.kambe@tier4.jp>

Author: veqcc

autoware_utils_geometry/src/geometry/ear_clipping.cpp

@@ -624,6 +624,10 @@ std::vector<alt::ConvexPolygon2d> triangulate(const alt::Polygon2d & poly)
 std::vector<Polygon2d> triangulate(const Polygon2d & poly)
 {
   const auto alt_poly = alt::Polygon2d::create(poly);
+  if (!alt_poly) {
+    return {};
+  }
+
   const auto alt_triangles = triangulate(alt_poly.value());
   std::vector<Polygon2d> triangles;
   for (const auto & alt_triangle : alt_triangles) {