Fix for LT-22315

[AndyBlack]

When an entry with a sense had a variant entry without a sense and that variant entry then had another variant entry without a sense, getting the gloss/sense of that third entry had a null reference error. This fixes that problem.

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This change is 

[github-actions]

LCM Tests

    16 files  ±0      16 suites  ±0   3m 1s ⏱️ +10s
 2 850 tests +1   2 830 ✅ +1   20 💤 ±0  0 ❌ ±0 
11 348 runs  +4  11 180 ✅ +4  168 💤 ±0  0 ❌ ±0 

Results for commit d67c946. ± Comparison against base commit a3b309c.

♻️ This comment has been updated with latest results.

[mark-sil]

@mark-sil reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @AndyBlack)

[mark-sil]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @AndyBlack)