Honestly you report that shit to the bank if you know what’s good for you, unless $100k is pocket change for you. If you go spending it, they will either get it back from you or you will go to jail for a number of years. Just about any court in the world will consider it the same as if you stole the money from the bank.

Just search and you’ll find numerous cases where that’s happened:
https://www.google.com/search?q=man+gets+million+in+bank+error