#3636 refactor: Improve type narrowing for null streamp map expressions Pull request opened by edgarrmondragon SSIA Summary by Sourcery Refine handling of null-valued stream map expressions to improve type safety and clarity. Bug Fixes: • Correct null and NULL_STRING comparison logic when processing stream map definitions to avoid unintended behavior. Enhancements: • Remove an unnecessary type ignore by tightening the expression type used in stream map evaluation. meltano/sdk