Fix: Handle optional api_key_id in Redis instance deletion

[ttien0181]

Description of Changes

This pull request resolves a database error encountered when deleting a Redis instance that does not have an associated API key. The API would previously return the error: Database field error: error occurred while decoding column "api_key_id": unexpected null; try decoding as an 'Option'.

Root Cause

In the delete_redis_instance handler within redis_instances.rs, the code attempted to extract the value of api_key_id and directly cast it to Uuid, a type that does not permit NULL values. While the RedisInstance struct was correctly defined to handle an Option<Uuid>, the sqlx::query combined with try_get bypassed this optionality check, leading to the decoding error when a NULL value was encountered in the database.

Solution

• Update Data Type: The api_key_id variable is now declared as Option<Uuid> to correctly handle the optional nature of the database field.
• Implement Null-Safety: An if let statement has been added to conditionally execute the UPDATE query on the api_keys table only when an api_key_id is present (is not None).

This change ensures a robust and reliable deletion process, preventing crashes for instances with no API key linked.