multi-region-dr: pd leader panic repeatly

[mayjiang0203]

Bug Report

What did you do?

What did you expect to see?

What did you see instead?

[2022/09/11 13:18:38.927 +00:00] [INFO] [operator_controller.go:450] ["add operator"] [region-id=86007] [operator="\"rule-split-region {split: region 86007 use policy USEKEY and keys [7480000000000000FF5800000000000000F8]} (kind:split, region:86007(61, 39), createAt:2022-09-11 13:18:38.92786507 +0000 UTC m=+116.187335222, startAt:0001-01-01 00:00:00 +0000 UTC, currentStep:0, size:1, steps:[split region with policy USEKEY])\""] [additional-info="{\"region-end-key\":\"7480000000000000FF5900000000000000F8\",\"region-start-key\":\"7480000000000000FF5700000000000000F8\"}"]
[2022/09/11 13:18:38.928 +00:00] [INFO] [operator_controller.go:652] ["send schedule command"] [region-id=86007] [step="split region with policy USEKEY"] [source=create]
[2022/09/11 13:18:38.928 +00:00] [FATAL] [log.go:72] [panic] [recover="\"invalid memory address or nil pointer dereference\""] [stack="github.com/tikv/pd/pkg/logutil.LogPanic\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/pkg/logutil/log.go:72\nruntime.gopanic\n\t/usr/local/go/src/runtime/panic.go:838\nruntime.panicmem\n\t/usr/local/go/src/runtime/panic.go:220\nruntime.sigpanic\n\t/usr/local/go/src/runtime/signal_unix.go:818\ngithub.com/tikv/pd/server/schedule/checker.(*RuleChecker).fixLooseMatchPeer\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/server/schedule/checker/rule_checker.go:242\ngithub.com/tikv/pd/server/schedule/checker.(*RuleChecker).fixRulePeer\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/server/schedule/checker/rule_checker.go:156\ngithub.com/tikv/pd/server/schedule/checker.(*RuleChecker).CheckWithFit\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/server/schedule/checker/rule_checker.go:118\ngithub.com/tikv/pd/server/schedule/checker.(*Controller).CheckRegion\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/server/schedule/checker/checker_controller.go:96\ngithub.com/tikv/pd/server/cluster.(*coordinator).patrolRegions\n\t/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/pd/server/cluster/coordinator.go:149"]

What version of PD are you using (pd-server -V)?

/ # /pd-server -V
Release Version: v6.1.1
Edition: Community
Git Commit Hash: 4ab9c0e
Git Branch: heads/refs/tags/v6.1.1
UTC Build Time: 2022-08-23 08:25:18

[nolouch]

some region without leader will cause this issue.

[nolouch]

/assign @nolouch