Oh, you're right. I thought that was part of your code, because I saw you used a map :p This is actually an issue then.

Edit: node 8 disabled.

if you attempt function checkThreeAndTwo(array) {
return true
} on node v8 it throws you stderr.

There is no ?? operator in code above

Did you select node v18 at the top? If that doesn't fix it, maybe you modified sample tests?

Either way, you should include the actual error message, not just the line that caused the error. If I run your code with node 8, I get "SyntaxError: Unexpected token ?", which makes sense, because ?? didn't exist in earlier versions.

Changed node version to 18 and problem is solved

I have stderr even if function is primitive and return constant value

STDERR:
/home/codewarrior/index.js:42
(map, x) => map.set(x, (map.get(x) ?? 0) +

awesome kata

You are welcome! Part 2 just got approved. https://www.codewars.com/kata/665bf5790be3c249ffb9422b

I like this kata. Thank you