[Bug] Bal Persist fails when tries to retrieve record with a nonexistent associations

[daneshk]

Description

When fetching the record with a nonexistent associated entity, bal persist failed with an error.

Related Internal issue: https://github.com/wso2-enterprise/internal-support-ballerina/issues/812

Steps to Reproduce

• Add one-to-one relationship with two entities(A -> B and B is the relationship owner(B has the foreign key))
• Add a record to the A entity but not the B entity.
• When retrieving, Define the record to retrieve A entity with the associated B entity. It gives an error when trying to map the () value to the associated entity fields

Version

All newest versions

Environment Details (with versions)

No response