Check reference_id in description matches vector

[Omega3395]

When MatchAndAddToDatabase() is called with a frame that produces 0 HBST matchables (e.g., only 1-2 ORB keypoints detected, none passing the self-similarity check), matchAndAdd() returns early without updating descriptor_matches_. Subsequently, when GetTopKClosures() iterates through reference frames and calls ValidateClosure(), it throws std::out_of_range because that reference_id isn't present in the map.
Here I check if the reference id is actually present in descriptor_matches_. This seems to only happen in the latest version (the previous version extracted a lot more ORB keypoints).
I am using the algorithm with single scans of a Ouster OS1-128.

[saurabh1002]

Hey, could you push this small change so that I can merge and close this PR soon. There is also a Style-check error in the CI, you can run the pre-commit file to fix it.
Thanks!!