Missing existence check before creating a Guard

[Balaji-Parimelazhagan]

Problem:
The function directly adds a new GuardItem without checking if a record with the same name (or ID) already exists.
When such a record exists, db.commit() raises an exception, causing a 500 Internal Server Error.

Expected Behavior:
Before creating a new GuardItem, the function should query the database to check for existing entries with the same unique fields.

[CalebCourier]

Trying to create a non-unique guard should throw an error, but you are correct that the error should not be a 500; rather it should be a 409 Conflict. For upsert functionality use the PUT endpoint instead.