Ensure that null is not returned as the item when creating an imported fact-check with original media in the GraphQL API.

[caiosba]

Description

When handling existing media to determine whether the imported fact-check will be added to or appended to the existing media, there was a scenario where the media already contained a fact-check in the same language being imported. In that scenario, nil was being returned. This PR fixes the issue by ensuring that a new object is returned in such cases, allowing the validations to handle whether the object is persisted or fails.

Fixes: CV2-5804.

How has this been tested?

TDD. I added a unit test that was able to reproduce the issue.

Checklist

• I have performed a self-review of my own code
• I have added unit and feature tests, if the PR implements a new feature or otherwise would benefit from additional testing
• I have added regression tests, if the PR fixes a bug
• I have added logging, exception reporting, and custom tracing with any additional information required for debugging
• I considered secure coding practices when writing this code. Any security concerns are noted above.
• I have commented my code in hard-to-understand areas, if any
• I have made needed changes to the README
• My changes generate no new warnings
• If I added a third party module, I included a rationale for doing so and followed our current guidelines

[caiosba]

@vasconsaurus can you please also review this since you worked on the feature CV2-5441?

[vasconsaurus]

@caiosba so in this case a new object is returned, but in the end it's creation will eventually fail since a media with the fact-check in the same language already exists?

EDIT: I understand why we need to do this. But for some reason I think it looks confusing. Maybe it's the name new_pm. But I don't know what is bugging me 😅

[caiosba]

@vasconsaurus , an easier way to explain this, is: this method, at the model level, shouldn't know anything about the API where it's used. We can read its responsibility this way: "Given two items, choose which one to return given the existing and the new fact-check". Is it more clear put that way? :)