开票历史,空数据异常处理

lib/order/invoices_manage/invoices_history.dart

@@ -80,6 +80,7 @@ class _InvoicesHistory extends State<InvoicesHistory> {
           _map[(element.reviewerTime ?? element.createTime).toString().substring(0,7)] = [element];
         }
       });
+      if(_map.isNotEmpty)
       _timeList = _map.keys.toList().first;
       if ((baseData?.data?.records ?? []).isEmpty ||
           records.length.toString() == baseData.data.total)