Debug the following function that calculates the factorial of a number. Identify and fix the issue causing the function to return incorrect results for negative input values.

$```\{$r$\}$

# Buggy Function

get$\_$factorial $<-$ function$($n$)\{$

if $($n $==0)\{$

return$(1)$ # Clue: Buggy location, Control the statement here

$\}$ else $\{$

return$($n $*$ factorial$($n $-1))$

$\}$

$\}$

get$\_$factorial$(3)$ # works well

get$\_$factorial$(-3)$ # throws error

$```$