fix(planning_evaluator): fix crashes with empty trajectories (#6129)

Signed-off-by: Maxime CLEMENT <maxime.clement@tier4.jp>

Author: maxime-clem

evaluator/planning_evaluator/src/metrics/trajectory_metrics.cpp

@@ -125,7 +125,7 @@ Stat<double> calcTrajectoryLength(const Trajectory & traj)
 Stat<double> calcTrajectoryDuration(const Trajectory & traj)
 {
   double duration = 0.0;
-  for (size_t i = 0; i < traj.points.size() - 1; ++i) {
+  for (size_t i = 0; i + 1 < traj.points.size(); ++i) {
     const double length = calcDistance2d(traj.points.at(i), traj.points.at(i + 1));
     const double velocity = traj.points.at(i).longitudinal_velocity_mps;
     if (velocity != 0) {
@@ -158,7 +158,7 @@ Stat<double> calcTrajectoryAcceleration(const Trajectory & traj)
 Stat<double> calcTrajectoryJerk(const Trajectory & traj)
 {
   Stat<double> stat;
-  for (size_t i = 0; i < traj.points.size() - 1; ++i) {
+  for (size_t i = 0; i + 1 < traj.points.size(); ++i) {
     const double vel = traj.points.at(i).longitudinal_velocity_mps;
     if (vel != 0) {
       const double duration =