fix(app): 修复约课首页教练所属机构名称显示问题

- 增加对 AppSite 对象的非空检查
-仅在 AppSite 对象不为空时设置教练信息和机构名称- 优化代码结构，提高代码的健壮性和可读性

national-motion-module-system/national-motion-system-biz/src/main/java/org/jeecg/modules/app/service/impl/AppHomeServiceImpl.java

@@ -99,11 +99,14 @@ public class AppHomeServiceImpl implements IAppHomeService {
                         String str = appCategoryMapper.selectById(item).getName();
                         list.add(str);
                     });
-            instructorVO.setId(sysUser.getId())
-                    .setAvatar(sysUser.getAvatar())
-                    .setName(sysUser.getRealname()).setList(list)
-                    .setTeachingCount(appInstructor.getClassesNumber())
-                    .setOrgName(appSiteMapper.selectOne(Wrappers.<AppSite>lambdaQuery().eq(AppSite::getOrgCode, appInstructor.getOrgCode())).getName());
+            AppSite appSite = appSiteMapper.selectOne(Wrappers.<AppSite>lambdaQuery().eq(AppSite::getOrgCode, appInstructor.getOrgCode()));
+            if(null != appSite){
+                instructorVO.setId(sysUser.getId())
+                        .setAvatar(sysUser.getAvatar())
+                        .setName(sysUser.getRealname()).setList(list)
+                        .setTeachingCount(appInstructor.getClassesNumber())
+                        .setOrgName(appSite.getName());
+            }
 
             // 获取该教练的课程（最多取2个）
             List<AppCourses> courses = appCoursesMapper.selectList(