Corrected error output

cargo.out

@@ -1,9 +1,13 @@
    Compiling futuretest v0.1.0 (file:///mnt/d/GIT/futuretest)
-error[E0554]: #![feature] may not be used on the stable release channel
- --> src/main.rs:1:1
+error[E0271]: type mismatch resolving `<futures::FutureResult<std::result::Result<(), _>, ()> as futures::Future>::Item == ()`
+  --> src/main.rs:17:23
    |
-1 | #![feature(conservative_impl_trait)]
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+17 | fn create_future() -> impl Future<Item=(), Error=()> {
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found ()
+   |
+   = note: expected type `std::result::Result<(), _>`
+              found type `()`
+   = note: the return type of a function must have a statically known size
 
 error: aborting due to previous error