I face palmed so hard I blew a whole trough my head. So clean.

A problem with your code is not a kata issue, please read this: https://docs.codewars.com/training/troubleshooting/#works-but-no

And yes, you should usually provide your code to check what's wrong. You're using global vars, they keep their value between tests.

I am able to pass all examples tests locally, even when switchin to an old version of node. But the random tests cannot set property ? of undefined which is not an operation I am actually performing.

   1,  2,  3,  4,  5,  6,  7,  8,  9,
  10, 11, 12, 13, 14, 15, 16, 17, 18,
  19, 20, 21, 22, 23, 24, 25, 26, 27,
  28, 29, 30, 31, 32, 33, 34, 35, 36
]``` my output for the final example test.

Can also provide my code if required, would love to know what causes this error.