k3d: [BUG] k3d v4.0.0 cannot create a cluster w/o a load balancer

What did you do

• How was the cluster created?

  • k3d create cluster --servers 3 --no-lb

• What did you do afterwards?

  • k3d commands?
  • docker commands?
  • OS operations (e.g. shutdown/reboot)?

What did you expect to happen

I expected to be able to create a 3 node cluster w/o a load balancer.

Screenshots or terminal output

λ k3d cluster create --servers 3 --no-lb true
INFO[0000] Prep: Network
INFO[0000] Created network 'k3d-true'
INFO[0000] Created volume 'k3d-true-images'
INFO[0000] Creating initializing server node
panic: assignment to entry in nil map

goroutine 1 [running]:
github.com/rancher/k3d/v4/pkg/client.ClusterCreate(0x4e51800, 0xc000122000, 0x4e66020, 0x54b1d68, 0xc000151620, 0xc0001516a0, 0x0, 0x0)
	github.com/rancher/k3d/v4/pkg/client/cluster.go:431 +0x1a39
github.com/rancher/k3d/v4/pkg/client.ClusterRun(0x4e51800, 0xc000122000, 0x4e66020, 0x54b1d68, 0xc000151600, 0x0, 0x4e29120)
	github.com/rancher/k3d/v4/pkg/client/cluster.go:64 +0x15b
github.com/rancher/k3d/v4/cmd/cluster.NewCmdClusterCreate.func1(0xc000166b00, 0xc00047f300, 0x1, 0x4)
	github.com/rancher/k3d/v4/cmd/cluster/clusterCreate.go:128 +0x51c
github.com/spf13/cobra.(*Command).execute(0xc000166b00, 0xc00047f2c0, 0x4, 0x4, 0xc000166b00, 0xc00047f2c0)
	github.com/spf13/cobra@v1.1.0/command.go:854 +0x2c2
github.com/spf13/cobra.(*Command).ExecuteC(0x5472100, 0xc00013a010, 0x6, 0x6)
	github.com/spf13/cobra@v1.1.0/command.go:958 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	github.com/spf13/cobra@v1.1.0/command.go:895
github.com/rancher/k3d/v4/cmd.Execute()
	github.com/rancher/k3d/v4/cmd/root.go:91 +0x5a
main.main()
	github.com/rancher/k3d/v4/main.go:27 +0x25

Which OS & Architecture

• Linux, Windows, MacOS / amd64, x86, …? macOS

λ uname -a
Darwin weisjohn 19.6.0 Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64 x86_64 i386 MacBookPro15,1 Darwin

Which version of k3d

• output of k3d version

$ k3d version
k3d version v4.0.0
k3s version latest (default)

Which version of docker

• output of docker version and docker info

$ docker version
Client: Docker Engine - Community
 Cloud integration: 1.0.7
 Version:           20.10.2
 API version:       1.41
 Go version:        go1.13.15
 Git commit:        2291f61
 Built:             Mon Dec 28 16:12:42 2020
 OS/Arch:           darwin/amd64
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.2
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.13.15
  Git commit:       8891c58
  Built:            Mon Dec 28 16:15:28 2020
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.4.3
  GitCommit:        269548fa27e0089a8b8278fc4fc781d7f65a939b
 runc:
  Version:          1.0.0-rc92
  GitCommit:        ff819c7e9184c13b7c2607fe6c30ae19403a7aff
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

$ docker info
Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Build with BuildKit (Docker Inc., v0.5.1-docker)
  scan: Docker Scan (Docker Inc., v0.5.0)

Server:
 Containers: 91
  Running: 4
  Paused: 0
  Stopped: 87
 Images: 50
 Server Version: 20.10.2
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc io.containerd.runc.v2 io.containerd.runtime.v1.linux
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 269548fa27e0089a8b8278fc4fc781d7f65a939b
 runc version: ff819c7e9184c13b7c2607fe6c30ae19403a7aff
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 4.19.121-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 11.7GiB
 Name: docker-desktop
 ID: WRHM:3LMI:2HMB:6JNE:W5VH:6TVC:5MNA:HSI6:Z642:SREJ:K4CU:CGIO
 Docker Root Dir: /var/lib/docker
 Debug Mode: true
  File Descriptors: 73
  Goroutines: 70
  System Time: 2021-01-25T21:09:39.059923534Z
  EventsListeners: 3
 HTTP Proxy: gateway.docker.internal:3128
 HTTPS Proxy: gateway.docker.internal:3129
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false