[backend] fix: 修复异常处理和类型转换问题

frontend/node_modules/css-tree/lib/utils/clone.js

@@ -0,0 +1,21 @@
+import { List } from './List.js';
+
+export function clone(node) {
+    const result = {};
+
+    for (const key in node) {
+        let value = node[key];
+
+        if (value) {
+            if (Array.isArray(value) || value instanceof List) {
+                value = value.map(clone);
+            } else if (value.constructor === Object) {
+                value = clone(value);
+            }
+        }
+
+        result[key] = value;
+    }
+
+    return result;
+}