fix: 1-based indexing, babey

mute-interpreter/src/env/core.rs

@@ -334,7 +334,11 @@ pub(super) fn core() -> HashMap<String, Value> {
                     }
                 };
 
-                list.get(nth).unwrap().clone()
+                if nth < 1 {
+                    return Node::Error(format!("TypeError: expected positive int, got {}", nth));
+                }
+
+                list.get(nth - 1).unwrap().clone()
             }),
         ),
         (

mute-interpreter/src/evaluator.rs

@@ -474,7 +474,7 @@ mod test {
     // List Manipulation
     #[case("(first (list 1 2 3))", "1")]
     #[case("(last (list 1 2 3))", "3")]
-    #[case("(nth (list 1 2 3) 1)", "2")]
+    #[case("(nth (list 1 2 3) 2)", "2")]
     #[case("(push-front (list 1 2 3) 0)", "(0 1 2 3)")]
     #[case("(push-back (list 1 2 3) 4)", "(1 2 3 4)")]
     #[case("(pop-front (list 1 2 3))", "(2 3)")]