fs: improve error performance for `writeSync`
I worked on it because it seemed like there was still work left to do in https://github.com/nodejs/performance/issues/106.
confidence improvement accuracy (*) (**) (***)
fs/bench-writeSync.js n=100000 type='invalid' *** 116.41 % ±9.35% ±12.49% ±16.36%
fs/bench-writeSync.js n=100000 type='valid' 0.46 % ±6.13% ±8.16% ±10.62%
Be aware that when doing many comparisons the risk of a false-positive result increases.
In this case, there are 2 comparisons, you can thus expect the following amount of false-positive results:
0.10 false positives, when considering a 5% risk acceptance (*, **, ***),
0.02 false positives, when considering a 1% risk acceptance (**, ***),
0.00 false positives, when considering a 0.1% risk acceptance (***)