Fix for ipc closed error in tests

[DeMoorJasper]

In the tests there sometimes accurs an ipc closed while sending data error, this is due to the main thread being killed before the children died.
This should force-kill the children, preventing this from happening. Another solution is awaiting the super.end using a promise or callback but this caused many tests to fail and in theory this fix would be just as solid and will not wait for unused data to be received.

[codecov-io]

Codecov Report

Merging #591 into master will decrease coverage by 0.26%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##           master     #591      +/-   ##
==========================================
- Coverage   88.95%   88.69%   -0.27%     
==========================================
  Files          61       61              
  Lines        1902     1910       +8     
==========================================
+ Hits         1692     1694       +2     
- Misses        210      216       +6

Impacted Files	Coverage Δ
src/WorkerFarm.js	94.44% <100%> (+0.56%)	⬆️
src/worker.js	90.9% <33.33%> (-9.1%)	⬇️
src/Logger.js	32.72% <0%> (-5.46%)	⬇️
src/assets/RustAsset.js	89.28% <0%> (-1.2%)	⬇️

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[fathyb]

Fixes the issue for me, good job!

[devongovett]

The error still occurred for me, but in the child worker process not in the master. I added something to worker.js to handle the promise rejections and just ignore that error.