修改-中移接口学习内容-展板界面展板缩略图可为空

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

@@ -230,18 +230,20 @@ public class LearningProjectController extends BaseController {
                 lambdaQuery.eq(ExhibitionBoard::getPublished, true);
                 lambdaQuery.in(ExhibitionBoard::getId, list3);
                 List<ExhibitionBoard> exhibitionBoards = this.exhibitionBoardService.list(lambdaQuery);
-                // 被删除的展板名称
-                StringBuilder stringBuilder = new StringBuilder();
-                exhibitionBoards.forEach(s -> {
-                    stringBuilder.append(s.getName());
-                    if (exhibitionBoards.get(exhibitionBoards.size() - 1).equals(s)) {
-                        stringBuilder.append("，");
-                    } else {
-                        stringBuilder.append("、");
+                if (CollectionUtil.isNotEmpty(exhibitionBoards)) {
+                    // 被删除的展板名称
+                    StringBuilder stringBuilder = new StringBuilder();
+                    exhibitionBoards.forEach(s -> {
+                        stringBuilder.append(s.getName());
+                        if (exhibitionBoards.get(exhibitionBoards.size() - 1).equals(s)) {
+                            stringBuilder.append("，");
+                        } else {
+                            stringBuilder.append("、");
+                        }
+                    });
+                    return getFailResult("展板：" + stringBuilder + "被子学习内容使用，不能被删除，更新失败！");
                     }
-                });
-                return getFailResult("展板：" + stringBuilder + "被子学习内容使用，不能被删除，更新失败！");
-            }
+                }
         }
 
         LearningContent learningContent = LearningContent.builder()