forgotten `return` causes segfault

[paciorek]

This cause a seg fault. We should error trap or handle as R handles.

nf <- nFunction(
  function(x = 'numericScalar') {
    result <- x + x
   # missing return(result)
  }, returnType = 'numericScalar'
)
cnf <- nCompile(nf)
cnf(3)