[chuck-users] crashing VM on (<string> != null) test?

I'm so baffled that this must be easy. What is the proper test to see if a string is null? More to the point, why does the following code bomb out on the conditional test? "foo.txt" => string g; <<< g >>>; // prints '"foo.txt" : (string)' if (g != null) { // evidently crashes here with "[chuck](VM) NullPointerException (during string op)..." <<< "not null" >>>; } else { <<< "is null" >>>; }