panic:runtime error: invalid memory address or nil pointer

[loong95]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

dashboard页面“SQL语句分析”、“慢查询”；客户端执行select * from cluster_processlist

2. What did you expect to see? (Required)

功能正常使用

3. What did you see instead (Required)

SQL语句分析查询报错：

PD日志如下：

客户端查询cluster_processlist报错：

tidb-server日志如下：

进入慢查询页面，报错：

4. What is your TiDB version? (Required)

5.7.25-TiDB-v7.1.1

部署了两个集群，这个集群有问题，另一个集群没问题

[cfzjywxk]

/cc @LykxSassinator
It seems there's a crash at recordSlowStat, PTAL