yurthub can not running successfully when cert-mgr-mode set to "kubelet"

[lclxg]

the value of "cert-mgr-node" is hubslef in defalut， I want to test kubelet mode , so modify the yurhub.yml and add environment variable cert-mgr-node=kubelet，but the yurthub pod can not running with the error “panic: runtime error: invalid memory address or nil pointer dereference”

What you expected to happen: the yurthub running correctly with kubelet cert-mgr-mode

How to reproduce it (as minimally and precisely as possible):modify the yurhub.yml and add environment variable cert-mgr-node=kubelet

Anything else we need to know?:

Environment:

• OpenYurt version: 0.4
• Kubernetes version (use kubectl version): 1.20
• OS (e.g: cat /etc/os-release): centos 8.3
• Kernel (e.g. uname -a):
• Install tools:
• Others:

others
/kind question

[rambohe-ch]

@lclxg Thank you for filing issue.
Would you upload the detail log of yurthub?

[qclc]

@lclxg Thanks for reporting the bug. This error occurred in the process of using kubelet.conf to obtain *rest.Config, I will fix it.

[qclc]

/kind bug