🎩 What? Why?

When the user tries to join a meeting that they are already following, the server will raise the following validation error:

      Failure/Error: Decidim::CreateFollow.call(follow_form, user)
      
      ActiveRecord::RecordInvalid:
        Validation failed: User has already been taken

This fixes the issue by changing the Decidim::CreateFollow command to check if the user is already following the followable item before creating the follow.

Testing

• Create meetings component with registrations enabled
• Login to the system and go to a meeting that has registration
• Follow the meeting
• Try to register for the event (either with form or without)

📋 Checklist

• ❓ CONSIDER adding a unit test if your PR resolves an issue.
• ✔️ DO check open PR's to avoid duplicates.
• ✔️ DO keep pull requests small so they can be easily reviewed.
• ✔️ DO build locally before pushing.
• ✔️ DO make sure tests pass.
• ✔️ DO make sure any new changes are documented in docs/.
• ✔️ DO add and modify seeds if necessary.
• ✔️ DO add CHANGELOG upgrade notes if required.
• ✔️ DO add to GraphQL API if there are new public fields.
• ✔️ DO add link to MetaDecidim if it's a new feature.
• ❌AVOID breaking the continuous integration build.
• ❌AVOID making significant changes to the overall architecture.