"invalid memory address or nil pointer dereference" in vpc_nat.go

[ShaPoHun]

Expected Behavior

Kube-ovn-controller is running normally.

Actual Behavior

E0331 11:06:55.728960       7 runtime.go:79] Observed a panic: "invalid memory address or nil pointer dereference" (runtime error: invalid memory address or nil pointer dereference)
goroutine 3180 [running]:
k8s.io/apimachinery/pkg/util/runtime.logPanic({0x55d189ce76c0?, 0x55d18b698800})
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/runtime/runtime.go:75 +0x99
k8s.io/apimachinery/pkg/util/runtime.HandleCrash({0x0, 0x0, 0x194?})
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/runtime/runtime.go:49 +0x75
panic({0x55d189ce76c0, 0x55d18b698800})
	/usr/local/go/src/runtime/panic.go:884 +0x213
github.com/kubeovn/kube-ovn/pkg/controller.(*Controller).resyncVpcNatConfig(0xc0007a76a0?)
	/github/kube-ovn/pkg/controller/vpc_nat.go:20 +0x7a
github.com/kubeovn/kube-ovn/pkg/controller.(*Controller).startWorkers.func6()
	/github/kube-ovn/pkg/controller/controller.go:993 +0x1d
k8s.io/apimachinery/pkg/util/wait.BackoffUntil.func1(0x30?)
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/wait/wait.go:157 +0x3e
k8s.io/apimachinery/pkg/util/wait.BackoffUntil(0xc0007a7790?, {0x55d18a121a20, 0xc0035215c0}, 0x1, 0xc00054e0c0)
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/wait/wait.go:158 +0xb6
k8s.io/apimachinery/pkg/util/wait.JitterUntil(0x0?, 0x3b9aca00, 0x0, 0x0?, 0x55d1870d7285?)
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/wait/wait.go:135 +0x89
k8s.io/apimachinery/pkg/util/wait.Until(0xc0007a77d0?, 0x55d18796ceea?, 0x0?)
	/root/go/pkg/mod/k8s.io/apimachinery@v0.26.3/pkg/util/wait/wait.go:92 +0x25
created by github.com/kubeovn/kube-ovn/pkg/controller.(*Controller).startWorkers
	/github/kube-ovn/pkg/controller/controller.go:992 +0x28f2
I0331 11:06:55.729024       7 network_attachment.go:66] parsePodNetworkAnnotation: kube-system/ovn-vpc-external-network, kube-system
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x110 pc=0x55d188c0a37a]

Steps to Reproduce the Problem

run master kube-ovn-controller