Panic on --disable-cluster-overview

[jeanlucmongrain]

Immediately when I run

$ octant --disable-cluster-overview
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x169e505]

goroutine 16 [running]:
github.com/vmware-tanzu/octant/internal/kubeconfig.NewKubeConfigContextManager(0x7991820, 0xc0001b5dd0, 0xc0000ca900, 0xd, 0x10, 0xc0000ca900, 0x8, 0x10)
	/__w/octant/octant/internal/kubeconfig/kubeconfig.go:65 +0xd5
github.com/vmware-tanzu/octant/pkg/dash.(*Runner).initAPI(0xc0000a40f0, 0x7991820, 0xc0001b5dd0, 0x79a8d60, 0xc00000d0e0, 0xc0000ce000, 0xd, 0x18, 0x0, 0x0, ...)
	/__w/octant/octant/pkg/dash/dash.go:339 +0x1721
github.com/vmware-tanzu/octant/pkg/dash.(*Runner).apiFromKubeConfig(0xc0000a40f0, 0xc000055360, 0x19, 0xc0000ce000, 0xc, 0x18, 0x7991820, 0xc0001b5dd0, 0x1, 0xc0004923d1, ...)
	/__w/octant/octant/pkg/dash/dash.go:262 +0x173
github.com/vmware-tanzu/octant/pkg/dash.NewRunner(0x7991760, 0xc0001388c0, 0x79a8d60, 0xc00000d0e0, 0xc0000ce000, 0xc, 0x18, 0x3, 0xc00048c240, 0x0)
	/__w/octant/octant/pkg/dash/dash.go:237 +0x7d7
github.com/vmware-tanzu/octant/internal/commands.newOctantCmd.func1.1(0x791b57c, 0x6, 0x79781e0, 0x28, 0x79244d0, 0x14, 0x7989de0, 0xc000488060, 0x7991760, 0xc0001388c0, ...)
	/__w/octant/octant/internal/commands/dash.go:125 +0xa06
created by github.com/vmware-tanzu/octant/internal/commands.newOctantCmd.func1
	/__w/octant/octant/internal/commands/dash.go:76 +0x5ed

it work fine if I don't use that cli flag

Environment:

• Octant version (use octant version): 0.17.0
• Kubernetes version (use kubectl version): 1.18
• OS (macOS 10.15, Windows 10, Ubuntu 19.10 etc): Ubuntu 20.04