adjust os exit

[kimschles]

Fixes issue #141

What this PR does and why we need it

I updated the CreateResourceProviderFromCluster function to find the KubeConfig and return an error if there is an issue retrieving the data. I wasn't able to figure out how to return the empty ResourceProvider, so I returned nil instead. Let me know if the empty ResourceProvider is necessary and I'll figure that out.

See line 132 for the specific line I'm referring to: https://github.com/reactiveops/polaris/compare/ks/adjust-os-exit?expand=1#diff-5524e4ddda8206adfe02f6a98ed7160eR132

[rbren]

Looks great, thanks Kim!

The caller will likely just bail out if an error is returned (as currently happens in main.go and dashboard.go), so no need for an empty ResourceProvider.

[rbren]

Also, for future reference, I think you could do something like return &ResourceProvider{}. But it's probably better to return null in this context.