fix(path_distance_calculator): do not calculate distance when too short path is subscribed

[tkimura4]

Description

Do not calculate distance when too short path is subscribed to avoid process-death by invalid access here

    const double distance =
      motion_utils::calcSignedArcLength(path->points, pose->pose.position, path->points.size() - 1);

Related links

TERIV Internal

Tests performed

I confirmed that the path_distance_calculator node works normally using the planning simulator.
$ros2 launch path_distance_calculator path_distance_calculator.launch.xml

(But I didn't test that the node didn't die when a too short path is subscribed.)

Notes for reviewers

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.
• The PR has been properly tested.
• The PR has been reviewed by the code owners.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.
• The PR is ready for merge.

After all checkboxes are checked, anyone who has write access can merge the PR.

[codecov]

Codecov Report

Base: 11.62% // Head: 11.62% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (85a3ab8) compared to base (14979d0).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2892   +/-   ##
=======================================
  Coverage   11.62%   11.62%           
=======================================
  Files        1321     1321           
  Lines       92140    92139    -1     
  Branches    24443    24443           
=======================================
  Hits        10714    10714           
+ Misses      70244    70243    -1     
  Partials    11182    11182           

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <0.00%> (?)
total	11.62% <ø> (+<0.01%)	⬆️	Carriedforward from 575decb

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
...stance_calculator/src/path_distance_calculator.cpp	0.00% <0.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[tkimura4]

@isamu-takagi @yabuta
Could you review this?

[isamu-takagi]

LGTM. I leave it up to you to reflect the comments.