[FIX] Bincount: Fix crash on array with all nans

[pavlin-policar]

Issue

Utility version of bincount crashed on sparse vector of all NaNs.

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #2831 into master will decrease coverage by 0.22%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2831      +/-   ##
==========================================
- Coverage   81.95%   81.72%   -0.23%     
==========================================
  Files         321      326       +5     
  Lines       54841    55703     +862     
==========================================
+ Hits        44946    45526     +580     
- Misses       9895    10177     +282

[nikicc]

I approve the code changes.

The test, however, doesn't really tests the change since it is missing implicit zeros. Looking at the codecov shows that the newly-added line is not covered.

[pavlin-policar]

Thanks! I've had to change the dense_sparse decorator so it would, in addition to the previous ways it ran tests, also run test for sparse array with no explicit zeros. Otherwise any test I wrote for bincount would be pointless, since it only crashed when the only value in the array was NaN.

[nikicc]

@pavlin-policar looks good to me.