Fehler didn't support returning `Result<Box<dyn Trait>, _>`

[earthengine]

Code:

use fehler::throws;

trait FooTrait {}
struct FooStruct;
struct FooError;
impl FooTrait for FooStruct {}
#[throws(FooError)]
fn foo() -> Box<dyn FooTrait> {
    Box::new(FooStruct)
}

Compile result:

Error[E0271]: type mismatch resolving ...
    |
104 | #[throws(FooError)]
    | ^^^^^^^^^^^^^^^^^^^^^^ expected trait object `dyn mymodule::FooTrait`, found struct `mymodule::FooStruct`
    |
    = note: expected type `std::boxed::Box<dyn mymodule::FooTrait>`
             found struct `std::boxed::Box<mymodule::FooStruct>`
    = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

[withoutboats]

It should work if you add as Box<dyn FooTrait> to the return expression, but its frustrating that the cast doesn't happen automatically here the way it normally would. Can you build against master and see if the problem persists?

[withoutboats]

A possible fix for this issue would be to change the expansion of return expressions from wrapping in ok to wrapping in ok and casting to the ret type.