fix(course-page): handle null autofixRequests safely

Ensure lastSubmission.autofixRequests defaults to an empty array when null.
This prevents runtime errors during filtering non-staff autofix requests and
improves the stability of the test-results-bar component.

Author: rohitpaulk

app/components/course-page/test-results-bar/index.ts

@@ -47,7 +47,7 @@ export default class TestResultsBar extends Component<Signature> {
     const courseStageStep = this.args.activeStep as CourseStageStep;
 
     return (
-      this.args.repository.lastSubmission?.autofixRequests
+      (this.args.repository.lastSubmission?.autofixRequests || [])
         .filter((request) => !request.creatorTypeIsStaff)
         .filter((request) => request.submission === this.args.repository.lastSubmission)
         .filter((request) => request.submission.courseStage === courseStageStep.courseStage)