bug fixed

src/main/java/cn/chnmuseum/party/web/controller/ChinaMobileRestApiController.java

@@ -608,10 +608,12 @@ public class ChinaMobileRestApiController extends BaseController {
                     .eq(LearningContent::getPublished, true).orderByDesc(LearningContent::getSortorder);
             lambdaQueryWrapper.select(LearningContent::getName, LearningContent::getCover);
             List<LearningContent> learningContentList = this.learningContentService.list(lambdaQueryWrapper);
+            if (!learningContentList.isEmpty()) {
                 String learningContentNames = learningContentList.stream().map(LearningContent::getName).collect(Collectors.joining("、"));
                 learningProject.setThumbnail(learningContentList.get(0).getCover());
                 learningProject.setLearningContentNames(learningContentNames);
             }
+        }
         return getResult(page);
     }