In the below example, what exactly makes a transaction active and valid even though it has reached the catch block due to an error?

USE AdventureWorks2022;  
GO  
  
-- SET XACT_ABORT ON will render the transaction uncommittable  
-- when the constraint violation occurs.  
SET XACT_ABORT ON;  
  
BEGIN TRY  
    BEGIN TRANSACTION;  
        -- A FOREIGN KEY constraint exists on this table. This   
        -- statement will generate a constraint violation error.  
        DELETE FROM Production.Product  
            WHERE ProductID = 980;  
  
    -- If the delete operation succeeds, commit the transaction. The CATCH  
    -- block will not execute.  
    COMMIT TRANSACTION;  
END TRY  
BEGIN CATCH  
    -- Test XACT_STATE for 0, 1, or -1.  
    -- If 1, the transaction is committable.  
    -- If -1, the transaction is uncommittable and should   
    --     be rolled back.  
    -- XACT_STATE = 0 means there is no transaction and  
    --     a commit or rollback operation would generate an error.  
  
    -- Test whether the transaction is uncommittable.  
    IF (XACT_STATE()) = -1  
    BEGIN  
        PRINT 'The transaction is in an uncommittable state.' +  
              ' Rolling back transaction.'  
        ROLLBACK TRANSACTION;  
    END;  
  
    -- Test whether the transaction is active and valid.  
    IF (XACT_STATE()) = 1  
    BEGIN  
        PRINT 'The transaction is committable.' +   
              ' Committing transaction.'  
        COMMIT TRANSACTION;     
    END;  
END CATCH;  
GO