fix: 修复切换选项可能报修改只读属性的问题

packages/amis-ui/src/components/Tree.tsx

@@ -210,6 +210,7 @@ export class TreeSelector extends React.Component<
   unfolded: WeakMap<Object, boolean> = new WeakMap();
   // key: child option, value: parent option;
   relations: WeakMap<Option, Option> = new WeakMap();
+  levels: WeakMap<Option, number> = new WeakMap();
 
   dragNode: Option | null;
   dropInfo: IDropInfo | null;
@@ -287,6 +288,11 @@ export class TreeSelector extends React.Component<
     }
   }
 
+  componentWillUnmount(): void {
+    // clear data
+    this.relations = this.unfolded = this.levels = new WeakMap() as any;
+  }
+
   /**
    * 展开懒加载节点的父节点
    */
@@ -877,11 +883,9 @@ export class TreeSelector extends React.Component<
           flattenedOptions.push(item);
         } else if (this.isUnfolded(parent)) {
           this.relations.set(item, parent);
+          this.levels.set(item, level);
           // 父节点是展开的状态
-          flattenedOptions.push({
-            ...item,
-            level
-          });
+          flattenedOptions.push(item);
         }
       }
     );
@@ -1102,7 +1106,7 @@ export class TreeSelector extends React.Component<
           ? 'folder'
           : 'file'
         : false);
-    const level = item.level ? item.level - 1 : 0;
+    const level = this.levels.has(item) ? this.levels.get(item)! - 1 : 0;
 
     let body = null;