fix collection if deleted

[atmonshi]

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[what-the-diff]

PR Summary

• Update to Field Retrieval Logic in 'FieldsContract.php'
  The process for gathering field collection items has been improved. Now, it accommodates both Field and FieldPreset instances. To achieve this, it now queries two different models depending on the instance - one for FieldPreset instances and another for Field instances, bringing more robustness to our system. The information obtained is then organized and provided as a collection. This change makes the system better at indexing and sorting data, enhancing overall data management.