That's the first "wait, what?". However, if you actually try and work out that horrible if statement

    !((_ok) ? true : (Math.random() > 0.1))

    _ok ? false : !(Math.random() > 0.1)

    !_ok && Math.random() <= 0.1

Seems fine...until you realise that this is the condition to exit early, it's still logging 90% of the time which is almost certainly not the desired behavior.

Not to mention _ok is a terrible name for that variable, and it's only ever being used as a negation. Why isn't it called _error or something?