fix(sdk): capture loader ref in unpackGroup to prevent race condition on done() cleanup

packages/sdk/lib/core/loader/Package.ts

@@ -1337,6 +1337,9 @@ export class Package {
         //const db = window.VIEWPORT.modules["db"];
         //const dbTable = `${useProjectState.getState().sceneId}-${useProjectState.getState().info.id}`;
 
+        // 在调用时捕获 loader 引用，防止 done() 清除 this.loader 后重试路径报错
+        const loader = this.loader;
+
         // map 存储 json 解析完成后执行的 function; key 为 uuid
         const funcMap = new Map<string, Function>();
 
@@ -1433,7 +1436,8 @@ export class Package {
 
         const parse = (json) => {
             if (check(json.object, json)) {
-                this.loader.parse(json, (group) => {
+                if (!loader) return;
+                loader.parse(json, (group) => {
                     const bones: Bone[] = [];
                     group.getObjectsByProperty("type", "Bone", bones);
                     if (bones.length > 0) {