Fix crash when Administrator has custom field that is internal but not readonly

[toBeOfUse]

Description

This fixes #3158.

Previously, the addActiveAdministratorCustomFields function, which adds the custom fields for the Administrator entity into the input type for the updateActiveAdministrator mutation, would assume that the UpdateAdministratorCustomFieldsInput type exists if there are any non-readonly custom fields, even if those custom fields are internal. This was incorrect, since internal custom fields will not appear in mutation input types, any more than ones that are readonly. So, the schema produced would reference that input type, causing a crash if it did not exist, which happened every time there were internal, non-readonly custom fields.

I also added a test to confirm that the UpdateAdministratorCustomFieldsInput type is not referenced when the Administrator entity has only an internal custom field.

Also, an irrelevant typo is fixed.

Breaking changes

Does this PR include any breaking changes we should be aware of?

Nope.

Checklist

📌 Always:

• I have set a clear title
• My PR is small and contains a single feature
• I have checked my own PR

👍 Most of the time:

• I have added or updated test cases
• I have updated the README if needed

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
docs	✅ Ready (Inspect)	Visit Preview	Oct 22, 2024 0:45am

[michaelbromley]

Thanks for this contribution. Everything is perfect - a very good, detailed issue which was easy for me to reproduce, a PR which includes tests, & a concise PR summary. Very well done 🙌