If cluster doesn't exist return an error message.

[lynnemorrison]

Prints and error message instead of just printing headers with no data.

 fixes issue #2047

[nluaces]

It shouldn't show an error, it should show the version of the images that we have by default.

[lynnemorrison]

@nluaces from Issue #2047 it says:

"1. if the intention is to show the running versions, an error message should be shown stating that the operation cannot be completed, as the cluster is not accessible.
2. for baked-in images and environment variables, the command should return its information, in full, as it does not depend on the cluster."

So that is why I changed to an error message. I will change to just showing the default instead if that is the better solution.

[nluaces]

@lynnemorrison the current version command is showing default images if skupper does not find a running container to which retrieve its version.

These images are being shown as the recommended versions that work with the skupper CLI version (examples: network-observer and its dependencies).

With other platforms that does not require a cluster like podman, the version command shows the default version (if I remember correctly).

In the meantime, I suggest to show the default versions if there is no cluster running for kubernetes environments.

How to show what type of version is an issue that still needs definition #2019

and should be done in a different pull request.

[lynnemorrison]

@nluaces Thanks for the clarification, will do!!