My code (JavaScript) failed on some tests, and I discovered that this happened because one or more of the arrays provided were empty, although the description mentioned that this couldn't happen. Anyway, I changed my code to treat empty arrays as hands with 0 score, but my code still failed. Then, I found out that this happened because the players with no cards in their hands were supposed to win! I don't know if the empty arrays are provided on purpose, but your algorithm is not correct, as it considers players with empty hands winners.

EDIT: I later found out that players with empty hands are only considered winners when the croupier's score is greater than 21.

The initial setup for JS is unnecessary complicated. Instead, a single function can be used, like this:

function getPerimeter(width, length){
  // Your code goes here
}

or this:

const getPerimeter = (width, length) => {
  // Your code goes here
}

As this kata is too simple, it will appeal more to beginners. The simple syntax will be more helpful for them, as they might not understand the complicated initial code.

Sample tests for BF should be added.
Current ones do nothing.

Very simple and basic, not challenging at all.
Most languages already have built-in functions to check if a variable is an integer, so you should consider disabling them to make it more challenging.