it removes the character that was there previously i think

Without taking apart your code any further, please know that functions can return values (instead of just print them), and that is expected here. Any outside platform for coding a challenge may differ in other ways, such as not having the same tests. So, generally, do not rely on them to perfectly match the expectations of this site. The tests you find here will be the final gateway to success. More colloquially, "But it works on my machine" is not going to get you very far. ;) Best of luck fixing your code, enjoy the site, and much happy coding.

Is something wrong with tests on this one? My code works perfectly fine when i run it in VS Code but it shows only errors when i run tests here

nice kata :)

Task
Find the minimum number of jumps to go from start to finish