Fixed ngettext validation

[AlexMost]

Fixes this issue - #132

[codecov]

Codecov Report

Merging #135 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
+ Coverage   96.61%   96.69%   +0.08%     
==========================================
  Files          15       15              
  Lines        1328     1330       +2     
  Branches      207      207              
==========================================
+ Hits         1283     1286       +3     
+ Misses         45       44       -1

Impacted Files	Coverage Δ
src/plugin.js	98.47% <ø> (+0.47%)	⬆️
src/extractors/ngettext.js	98.64% <100%> (+0.04%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c2b6e11...78c9a24. Read the comment docs.