Thanks for pointing it out, akar-0

What error ? If you don't tell what the error is, people won't be able to help you.

That being said, the error could arise from the fact that NaN is not equal to anything even itself :

NaN == NaN // False

If that is your issue, look how to check for NaN.

Ps : This kata has been retired, you will not get any points for solving it.

Hi. A suggestion means suggestion of improvement of the kata.

Your code would return true for something like nenenenene, which is obviously incorrect.