Confusing/incorrect type mismatch message in async CE

Consider this code (type annotations added for clarity):

```f#
async {
let asyncUnitArr : Async = async.Return [| () |]
do! asyncUnitArr
}
```

It fails to compile with this message on the second `asyncUnitArr`:

> This expression was expected to have type 'unit[]' but here has type 'unit'


I find this confusing for two reasons.

Firstly, the expression that is underlined, `asyncUnitArr`, has the type `Async`, so the message seems to be missing the `Async` wrapper.

Secondly, the wording/types seem to be switched around. The expression _has_ the type `Async` and (given the context) is _expected_ to have the type `Async`.

For comparison, here is a similar error message that seems to be correct:

```f#
let f (x: int) = ()
f ""
```