chore: clippy

src/vm/env.rs

@@ -67,7 +67,7 @@ impl Env {
     }
 
     pub fn leave(&self) {
-        let last = std::mem::replace(&mut *self.last.borrow_mut(), None).unwrap();
+        let last = (*self.last.borrow_mut()).take().unwrap();
         let _ = std::mem::replace(&mut *self.last.borrow_mut(), last.last.borrow().clone());
         let map = last.map.borrow().clone();
         *self.map.borrow_mut() = map;