Void methods and string extrapolation cause Invalid Program exception

>>> def method():
... a = 3
... a++
...
>>> print method()
----^
ERROR: No apropriate version of 'System.Console.WriteLine' for the argument list '(System.Void)' was found.
>>> print "$

"
Input1Module
>>> print "$

"
System.InvalidProgramException: Common Language Runtime detected an invalid program.
at Input4Module.Main(String[] argv)

Boo doesn't check the contents of string extrapolation parameters for void objects.
Instead, it cast them to object and try to use them. This compiles fine, but cause an error on runtime.