Faster, more readable, less nested and more consistent function

[siddharthborderwala]

@profnandaa I have updated the assertString utility function in src/lib/util/assertString.js.
The new function is more readable and has less nesting. It has less if/else nesting and also has a consistent error message (previously some error messages have "... received a [invalidType]" and some of them have "... received [invalidType]", now it is always "... received a [invalidType]").
I measured performances of the current function and the new function, it's a small margin but the new function is faster by 0.006 to 0.01 milliseconds on an average.

[codecov]

Codecov Report

Merging #1454 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1454      +/-   ##
==========================================
- Coverage   99.92%   99.92%   -0.01%     
==========================================
  Files          95       95              
  Lines        1268     1265       -3     
==========================================
- Hits         1267     1264       -3     
  Misses          1        1              

Impacted Files	Coverage Δ
src/lib/util/assertString.js	100.00% <100.00%> (ø)

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[profnandaa]

Thanks for your contribution! 🎉 /cc. @tux-tn @ezkemboi

[siddharthborderwala]

@profnandaa It was my pleasure to contribute to a library that is so vastly used! 😍

[profnandaa]

@siddharthborderwala -- see if you can address the code coverage drop issue...

[siddharthborderwala]

@profnandaa I generated the report locally and checked it, turns out the coverage issue is because of Line 89 in src/lib/isTaxID.js, apparently it is not getting hit according to the coverage report.

This is the report data for the directory in which I have changed files.

[profnandaa]

I see, thanks! I think we will have this addressed in an open related PR.

[siddharthborderwala]

Sounds okay. After updating this code, I ran npm run test and it caused a bunch of changes in other files because of the build steps I guess, should I commit and push those changes too? @profnandaa

[siddharthborderwala]

@profnandaa Could you please label this pull request as hacktoberfest-accepted , I would appreciate that a lot, thanks!

[profnandaa]

@siddharthborderwala -- thanks. Sure, the whole repo is opted into hacktoberfest, so this should count after landing even without the tag; let me know if it works.

[profnandaa]

/cc. @tux-tn @ezkemboi @rubiin