修复bug

Tiobon.Core.Services/Ghre/Ghre_CourseServices.cs

@@ -328,6 +328,7 @@ public class Ghre_CourseServices : BaseServices<Ghre_Course, Ghre_CourseDto, Ins
 
             list.ForEach(x =>
             {
+                if (!string.IsNullOrWhiteSpace(x.ExamPaperId))
                     x.ExamPaperIds = JsonHelper.JsonToObj<List<long>>(x.ExamPaperId);
             });
             result.result.DT_TableDataT1 = list;