Use lock in both index and remove operation.

vm/src/builtins/list.rs

@@ -300,8 +300,8 @@ impl PyList {
 
         if let Some(index) = index.into() {
             // defer delete out of borrow
-            let mut elements = self.borrow_vec_mut();
-            Ok((index < elements.len()).then(move || elements.remove(index)))
+            let is_inside_range = index < self.borrow_vec().len();
+            Ok(is_inside_range.then(|| self.borrow_vec_mut().remove(index)))
         } else {
             Err(vm.new_value_error(format!("'{}' is not in list", needle.str(vm)?)))
         }