Handle empty alias group case

[nikhilnishad-goog]

For this issue. Modifies repoowners.go to handle cases where the file has an alias group but does not have any user name listed in it.

There are multiple acceptable yamls that are being not parsed explictly and edge cases not handled. Examples are -

aliases:
  alias-group:

aliases:
  alias-group: {}

aliases:
  alias-group: {alias1, alias2}

aliases:
  alias-group: ""

All of these are valid yamls, that can cause silent failures like the one mentioned in #360 .

Fixes #360

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: nikhilnishad-goog / name: Nikhil Kumar Nishad (33fb5a1, b19c389, 1c567e6)

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[nikhilnishad-goog]

/ok-to-test

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[nikhilnishad-goog]

/assign @tuminoid

[matthyx]

/ok-to-test

[nikhilnishad-goog]

/test pull-prow-integration

[tuminoid]

Thanks for taking a look!

Took initial look at this, mostly nits.

I'm also thinking if we really should error out in unmarshalling the aliases, or just gracefully accept a group was empty and did not add any usernames. As a user, I'd kinda hate the fact that if I don't have any people left in a group, I'd need to comment out the alias and everywhere it is referred.

[nikhilnishad-goog]

@tuminoid Thanks for taking a look.

I'm also thinking if we really should error out in unmarshalling the aliases, or just gracefully accept a group was empty and did not add any usernames. As a user, I'd kinda hate the fact that if I don't have any people left in a group, I'd need to comment out the alias and everywhere it is referred.

I am in the opinion of throwing when unmarshalling, ideally, there should be no dead code (which includes empty groups that are not meant to have any effect anywhere). The tests should match that behavior.

Also, there are some missed cases, i will update the PR soon.

[jmguzik]

Suggested change

	members = append(members, member.(string))
	str, ok := member.(string)
	if !ok {
	return result, fmt.Errorf(....)
	}

type check here?