Notice: Set $N = 7$. Look closely at how many times the exact same subproblem (like fib(2) or fib(3)) is evaluated over and over again.

This redundancy is why recursive Fibonacci is an infamous example of beautiful code but terrible performance (Exponential Time).

The method simply returns 0 instantly. The compiler throws a SyntaxError. The recursion calls itself infinitely with negative numbers, eventually resulting in a StackOverflowError.