Doesn't work with GCP auth provider (GKE contexts)

[skeenan947]

I get this when trying to run:

Testing context's 'gke-skeenan-eaa3d8e68f' cluster...
error converting to clientset: failed to create API client: No Auth Provider found for name "gcp"
Remove 'gke-skeenan-eaa3d8e68f' from context (Y/n)? panic: reflect: call of reflect.Value.Type on zero Value

goroutine 75 [running]:
reflect.Value.Type(0x0, 0x0, 0x0, 0x1c81aa0, 0x1b5d640)
	/usr/local/Cellar/go/1.10.3/libexec/src/reflect/value.go:1713 +0x16d
github.com/ashleyschuett/kubeconfig-cleanup/vendor/github.com/imdario/mergo.Merge(0x1a85600, 0xc4203ec000, 0x1a85600, 0x0, 0xc42039c498, 0xc420396301)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/vendor/github.com/imdario/mergo/merge.go:95 +0x114
github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/client-go/tools/clientcmd.(*DirectClientConfig).getAuthInfo(0xc4203b2000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/client-go/tools/clientcmd/client_config.go:423 +0x2df
github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/client-go/tools/clientcmd.(*DirectClientConfig).ClientConfig(0xc4203b2000, 0x0, 0x0, 0x0)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/client-go/tools/clientcmd/client_config.go:113 +0x71
github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/kubernetes/cmd/kubeadm/app/util/kubeconfig.ToClientSet(0xc4203991a0, 0xc42039a6f0, 0x0, 0x0)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/vendor/k8s.io/kubernetes/cmd/kubeadm/app/util/kubeconfig/kubeconfig.go:80 +0x80
github.com/ashleyschuett/kubeconfig-cleanup/pkg/config.(*Manager).Validate(0xc4201ed500, 0xc42016c960, 0x0, 0x0, 0x0)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/pkg/config/config.go:163 +0x195
github.com/ashleyschuett/kubeconfig-cleanup/pkg/config.(*Manager).ValidateAndAddToWorkqueue(0xc4201ed500, 0xc42033e5b0, 0x7, 0xc42016c960)
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/pkg/config/workqueue.go:26 +0x3c
created by github.com/ashleyschuett/kubeconfig-cleanup/pkg/config.(*Manager).Run
	/Users/ashley/go/src/github.com/ashleyschuett/kubeconfig-cleanup/pkg/config/config.go:64 +0xc1