You've probably already tried this, but just in case: maybe you can pre-catch the error, such as
If( not symmetric(x), ., rest of formula(x))
If it's any consolation, the JMP 12 beta will turn on Ignore Errors automatically when you set a problem formula via script. I tried:
Column( "X" ) << Set Formula( If( Random Uniform( 0, 1 ) < 0.5, Foo(), 1 ) );