There is the try() command, as part of the try-catch structure, but I think that only works for error-trapping, not warning-trapping. That would be a nice feature.
You should be able to use the lastwarn() command to create something like the same thing. Specifically, I am thinking you could execute the lastwarn() command just after your code, and use the output to determine whether to assign your "fall back" value.
