duplicate "namespace:" entries in kustomization.yaml should get detected

[guettli]

Eschewed features

• This issue is not requesting templating, unstuctured edits, build-time side-effects from args or env vars, or any other eschewed feature.

What would you like to have added?

If this is in my kustomization.yaml file, I would like to get an error:

namespace: foo
namespace: bar

Why is this needed?

This helps me to find errors early.

Can you accomplish the motivating task without this feature, and if so, how?

After some time I will find that error.

What other solutions have you considered?

.

Anything else we should know?

No response

Feature ownership

• I am interested in contributing this feature myself! 🎉

[k8s-ci-robot]

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