How can I avoid the #N/A when I use a cubeset expression to exclude a member of a dimension that may or may not be present?

For example I have dimension with the US City: New York, Chicago, El Paso, Miami, …
I want to be able to exclude “Los Angeles” so I do =CUBESET(CUBE,”-{[US CITY].[Los Angeles]}”)
but if Los Angeles is not a member of the dimension then I get an error (which is normal I guess), how can I avoid that ?

Thank you