task executor panic when checking task

[D3Hunter]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

run task with 2 tidb

as the task has finished and moved into history table

[2023/12/28 01:10:02.912 +08:00] [ERROR] [task_executor.go:128] ["BaseTaskExecutor panicked"] [task-id=60003] [recover="runtime error: invalid memory address or nil pointer dereference"] [stack="github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor.(*BaseTaskExecutor).Run.func1
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor/task_executor.go:128
runtime.gopanic
    /usr/local/go/src/runtime/panic.go:914
runtime.panicmem
    /usr/local/go/src/runtime/panic.go:261
runtime.sigpanic
    /usr/local/go/src/runtime/signal_unix.go:861
github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor.(*BaseTaskExecutor).run
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor/task_executor.go:240
github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor.(*BaseTaskExecutor).Run
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor/task_executor.go:136
github.com/pingcap/tidb/pkg/disttask/importinto.(*importExecutor).Run
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/importinto/task_executor.go:482
github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor.(*Manager).onRunnableTask
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor/manager.go:405
github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor.(*Manager).onRunnableTasks.func1
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor/manager.go:230
github.com/pingcap/tidb/pkg/resourcemanager/pool/spool.(*Pool).run.func1
    /home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/pkg/resourcemanager/pool/spool/spool.go:144"]

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)