Mof operations with no return type generates bad code.
A MOF operation with no return type is translated to
a call inside a method needing a return type.
To reproduce that, simply declare in a class a method
with no return type. The generated code doesn't compile
and point to the problem.
I have no patch for now.
A workaround is to declare a return type, and let the
method return anything (ex: null).