I have a suggestion pertaining the testing process in kata - specifically, the lack of any feedback whenever the code execution on the server times out.
This specifically annoyed me because I'm struggling with a kata where my code is timing out, and I want to debug it, to test at least how far my code got before it timed out, but whenever the code times out, you only receive one message - that the code execution timed out. Not even the console log.
I don't think it would be particularly hard to simply return what the program wrote before it was terminated automatically by the server, even though I don't know how exactly it works.

Pretty neat, but were 4000 tests really necessary? lol

are the tasting cases thoroughly checked?
I'm pretty sure that a prime pair with a gap of 6 exists between 100 and 110, and it's [101, 107]. Both of these numbers are primes, and the gap between them is 6. Why is the expected output null?
Edit - nevermind, I've looked at the instructions - the kata defines a pair of primes as two consecutive primes. Between those two numbers is another prime, 103, and that's why the expected output is null. Sorry for the stupid question.