av pr create fails if the parent branch is merged and not synced

[draftcode]

It's better to detect this and explain that rather than saying "Head sha can't be blank, Base sha can't be blank, No commits between buildkite_pipeline_config_api and buildkite_api_token, Base ref must be a branch"

[Konboi]

I have a question about this issue.
Do you suggest handling the error messages from the API (GraphQL Error message) in more detail? Or do you have any other ideas?

[draftcode]

Let's first try checking if the parent is merged by checking MergeCommit in the branch metadata.