fix：加群报错

mec-biz/src/main/java/com/ym/mec/biz/service/impl/ImGroupMemberServiceImpl.java

@@ -111,7 +111,7 @@ public class ImGroupMemberServiceImpl extends BaseServiceImpl<Long, ImGroupMembe
 		Map<Integer, String> nameIdMap= MapUtil.convertIntegerMap(teacherDao.queryNameByIdList(new ArrayList<>(userRoleMap.keySet())));
 		for (Entry<Integer, String> entry : userRoleMap.entrySet()) {
 			
-			if(existUserIdList.contains(entry.getKey())){
+			if(existUserIdList.contains(entry.getKey())||Objects.isNull(entry.getKey())){
 				continue;
 			}