Remove redundant tail call resolution

The `resolve_tail_calls` function is being called twice in some
execution paths, which is unnecessary and can lead to incorrect
behavior. This commit removes the redundant calls and simplifies the
execution flow.

src/ast/environment.rs

@@ -497,11 +497,7 @@ impl Environment {
                 purity: Purity::Impure,
                 func: Rc::new(move |args| {
                     let mut vm = VM::new(global_values.clone());
-                    let res = match vm.run_with_args(closure_obj.clone(), args) {
+                    match vm.run_with_args(closure_obj.clone(), args) {
-                        Ok(v) => v,
-                        Err(e) => panic!("Myc Runtime Error: {}", e),
-                    };
-                    match vm.resolve_tail_calls(&mut crate::ast::vm::NoOpObserver, Ok(res)) {
                         Ok(v) => v,
                         Err(e) => panic!("Myc Runtime Error: {}", e),
                     }
@@ -519,21 +515,18 @@ impl Environment {
                     Err(e) => panic!("Myc Runtime Error: {}", e),
                 };
 
-                let mut final_res = res;
+                if let Value::Object(obj) = &res
-                if let Value::Object(obj) = &final_res
                     && obj
                         .as_any()
                         .downcast_ref::<crate::ast::vm::Closure>()
                         .is_some()
                 {
-                    final_res = match vm.run_with_args(obj.clone(), args) {
+                    match vm.run_with_args(obj.clone(), args) {
                         Ok(v) => v,
                         Err(e) => panic!("Myc Runtime Error (Closure): {}", e),
-                    };
+                    }
-                }
+                } else {
-                match vm.resolve_tail_calls(&mut crate::ast::vm::NoOpObserver, Ok(final_res)) {
+                    res
-                    Ok(v) => v,
-                    Err(e) => panic!("Myc Runtime Error: {}", e),
                 }
             }),
         })

src/ast/vm.rs

@@ -229,7 +229,9 @@ impl VM {
         } else {
             self.unpack(&closure.parameter_node, args, &mut 0)?;
         }
-        self.eval(&closure.exec_node)
+        let result = self.eval(&closure.exec_node);
+        self.frames.pop();
+        self.resolve_tail_calls(&mut NoOpObserver, result)
     }
 
     pub fn run_with_args_observed<O: VMObserver>(
@@ -252,7 +254,9 @@ impl VM {
         } else {
             self.unpack(&closure.parameter_node, args, &mut 0)?;
         }
-        self.eval_observed(observer, &closure.exec_node)
+        let result = self.eval_observed(observer, &closure.exec_node);
+        self.frames.pop();
+        self.resolve_tail_calls(observer, result)
     }
 
     pub fn run_with_observer<O: VMObserver>(