[NewEntry] Prevent crash when duplicate vernacular is cleared

[imnasnainaec]

Fixes #3071

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This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 74.95%. Comparing base (bc9f532) to head (78a7923).

Files	Patch %	Lines
...s/DataEntry/DataEntryTable/NewEntry/VernDialog.tsx	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3072      +/-   ##
==========================================
- Coverage   74.97%   74.95%   -0.03%     
==========================================
  Files         269      269              
  Lines       10359    10361       +2     
  Branches     1225     1226       +1     
==========================================
- Hits         7767     7766       -1     
- Misses       2235     2236       +1     
- Partials      357      359       +2     

Flag	Coverage Δ
backend	84.03% <ø> (-0.03%)	⬇️
frontend	66.59% <50.00%> (-0.03%)	⬇️

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[jasonleenaylor]

Nice work figuring out how to test this.

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)