Fix bug

Author: BenLauwens

src/finitestatemachines/macro.jl

@@ -37,9 +37,13 @@ macro stateful(expr::Expr)
       $((:($arg) for arg in new_expr.args)...)
     end
   )
-  expr.args[1].head == Symbol("::") && func_expr.args[1] = Expr(Symbol("::"), func_expr.args[1], expr.args[1].args[2])
+  if expr.args[1].head == Symbol("::")
+    func_expr.args[1] = Expr(Symbol("::"), func_expr.args[1], expr.args[1].args[2])
+  end
   call_expr = deepcopy(expr)
-  call_expr.args[1].head == Symbol("::") && call_expr.args[1] = call_expr.args[1].args[1]
+  if call_expr.args[1].head == Symbol("::")
+    call_expr.args[1] = call_expr.args[1].args[1]
+  end
   call_expr.head = Symbol("=")
   call_expr.args[2] = :($type_name($((:($arg) for arg in args)...)))
   esc(quote