H-43: fix WEB Captain takeover E2E flow (#8)

* test(shangwutong): cover CID rename reliability

* H-43: fix WEB Captain takeover flow

* H-48: preserve compatible provider model

* H-49: make Captain takeover atomic

* H-50: prevent duplicate widget initialization

---------

Co-authored-by: Rogee <rogee@ipao.vip>

frontend/app/javascript/widget/mixins/messageMixin.js

@@ -2,7 +2,7 @@ export default {
   computed: {
     messageContentAttributes() {
       const { content_attributes: attribute = {} } = this.message;
-      return attribute;
+      return attribute || {};
     },
     hasAttachments() {
       return !!(

frontend/app/javascript/widget/mixins/specs/messageMixin.spec.js

@@ -34,4 +34,11 @@ describe('messageMixin', () => {
     expect(wrapper.vm.messageContentAttributes).toEqual({});
     expect(wrapper.vm.hasAttachments).toBe(true);
   });
+
+  it('normalizes null content attributes', () => {
+    const wrapper = shallowMount(Component, {
+      data: () => ({ message: { content_attributes: null } }),
+    });
+    expect(wrapper.vm.messageContentAttributes).toEqual({});
+  });
 });