Query can cause InvalidOperationException with message "The value 'RightOuter' of type BoundJoinType was unexpected"

[dallmair]

Sample query (it does not make sense, but should not crash NQuery either):

SELECT  *
FROM    Orders o
        RIGHT JOIN Categories c ON o.EmployeeID <= c.CategoryID

Root cause is the generation of a right outer join which is kept in the execution pipeline. Or, in other words, the missing Semi Join Simplification.