`TestDeadlockReportWaitChain` panic

[disksing]

https://github.com/tikv/client-go/pull/204/checks?check_run_id=2964207159

suite.go:63: test panicked: runtime error: invalid memory address or nil pointer dereference
        goroutine 1363 [running]:
        runtime/debug.Stack(0xc000423590, 0x278bce0, 0x43b5110)
        	/opt/hostedtoolcache/go/1.16.5/x64/src/runtime/debug/stack.go:24 +0xab
        github.com/stretchr/testify/suite.failOnPanic(0xc000188780)
        	/home/runner/go/pkg/mod/github.com/stretchr/[email protected]/suite/suite.go:63 +0x6d
        panic(0x278bce0, 0x43b5110)
        	/opt/hostedtoolcache/go/1.16.5/x64/src/runtime/panic.go:971 +0x499
        integration_tests_test.(*testLockSuite).TestDeadlockReportWaitChain(0xc000833a40)
        	/home/runner/work/client-go/client-go/integration_tests/lock_test.go:783 +0x8e6
        reflect.Value.call(0xc0008a9320, 0xc000123c20, 0x13, 0x29f903f, 0x4, 0xc000687e20, 0x1, 0x1, 0xc0007338a0, 0xc0007338a0, ...)
        	/opt/hostedtoolcache/go/1.16.5/x64/src/reflect/value.go:476 +0x99c
        reflect.Value.Call(0xc0008a9320, 0xc000123c20, 0x13, 0xc000687e20, 0x1, 0x1, 0x39, 0xc000065438, 0x48deb0)
        	/opt/hostedtoolcache/go/1.16.5/x64/src/reflect/value.go:337 +0xd9
        github.com/stretchr/testify/suite.Run.func1(0xc000188780)
        	/home/runner/go/pkg/mod/github.com/stretchr/[email protected]/suite/suite.go:158 +0x392
        testing.tRunner(0xc000188780, 0xc00045efc0)
        	/opt/hostedtoolcache/go/1.16.5/x64/src/testing/testing.go:1193 +0x203
        created by testing.(*T).Run
        	/opt/hostedtoolcache/go/1.16.5/x64/src/testing/testing.go:1238 +0x5d8