Recursion Without a Floor

factorial(0) crashes the server with "Maximum call stack size exceeded".

factorial(n) returns n! for n ≥ 0. factorial(0) is 1.

Fix the code so every test passes. Keep the function name factorial.

Test cases

• factorial(5) → 120
• factorial(1) → 1
• factorial(0) → 1
• factorial(3) → 6

Stuck? Hints go from a nudge to the exact fix.