fix: 修复部分情况下topList接口报错的问题

servers/boe-server-all/src/main/java/com/xboe/module/course/service/impl/CoursePageServiceImpl.java

@@ -119,7 +119,7 @@ public class CoursePageServiceImpl implements ICoursePageService {
         }
         return courseList.stream()
                 .map(c -> convertToVo(c, courseTeacherList))
-                .sorted(Comparator.comparing(CoursePageVo::getSortWeight)) // 按照sortWeight字段进行排序
+                .sorted(Comparator.comparing(CoursePageVo::getSortWeight, Comparator.nullsLast(Comparator.naturalOrder())))
                 .collect(Collectors.toList());
     }