Slice and Splice not passing test for some reason

Tell us what’s happening:
As far as I can tell my code works when testing the tests however it doesn’t pass the tests for the challenge.

Any idea why?

Your code so far

function frankenSplice(arr1, arr2, n) {
  let arr3 = [];

  arr3.push(arr2.slice(0, n));
  arr3.push(arr2.slice(n, arr2.length+1));

  return arr3;

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36.

Link to the challenge:

Ahh think I know why as output is a array in a array its not clear on FCC console. Will try again