I've tested the stub code return "" and my solution, but this error is not producible, closing as of now. Do reraise a new issue if you find such cases.

well the logic they are using here is that "number of time each digit should be multiplied to itself = number of digits in the input"

did you rewrite the funcion call?
this happens to me when I do that and forget to export the function.

7^1 == 7 (power 1, because it has 1 digit), so it is a narcissistic number, and 1654 doesn't exist in any example (not in description, and in sample tests there is only 1634, which is same as 1^4 + 6^4 + 3^4 + 4^4).

Even if you were right, you should provide more information why they aren't, and why this is an issue. Currently it isn't.

But 7 is a narcissistic number? I also cannot see the 1654 being used as an example anywhere, where do you see it?