Missing machineSelectorConfig throws unhandled exception

[rak-phillip]

A missing machineSelectorConfig for an RKE2 cluster can cause the edit form to fail to render.

Steps to reproduce

• Navigate to Cluster Management and click on Create
• Select Custom
• Add a name to the cluster and click on "Edit as YAML"
• Update machineSelectorConfig to machineSelectorConfig: []
• Click Create
• Select the Overflow Menu for your newly created cluster and select "Edit Config"

Expected behavior

The edit form will render. If a missing machineSelectorConfig is an unexpected state, provide a warning to the user with information on how to resolve.

Actual behavior

The loading indicator is shown indefinitely, while an error is thrown in the browser console

Additional details

• Reported in Rancher 2.9.1
• The original report was for a recent install of Rancher v2.9.1; the cluster was created with terraform
• Rancher was installed with the agent TLS mode set to Strict
• The reproduction detailed above produces the same error as what was repported
• This behavior looks to have introduced in Changes for Azure cloud provider for RKE2 #11578

[rak-phillip]

@torchiaf can you provide more details on this error? I'm unsure if an empty machineSelectorConfig is a valid state, but it appears that there are ways to create RKE2 clusters that would put a cluster into this state.