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Problem with compilation

Hello.
I have a problem with this simple example:

/*
[dependencies]
fasteval2 = "2.1.1"
*/

use fasteval2::Compiler; // use this trait so we can call compile().
use fasteval2::EmptyNamespace;
use fasteval2::Evaler; // use this trait so we can call eval().

use std::collections::BTreeMap;

fn main() {
    let parser = fasteval2::Parser::new();
    let mut slab = fasteval2::Slab::new();
    let compiled = parser
        .parse("VALUE99 * VALUE77", &mut slab.ps)
        .unwrap()
        .from(&slab.ps)
        .compile(&slab.ps, &mut slab.cs, &mut EmptyNamespace);

    let mut map: BTreeMap<_, _> = BTreeMap::new();
    map.insert("VALUE99".to_string(), 2.0);
    map.insert("VALUE77".to_string(), 3.0);

    let val = fasteval2::eval_compiled!(compiled, &slab, &mut map);
    println!("{:?}", val);
}

error:

error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
  --> src/main.rs:20:15
   |
7  | fn main() {
   | --------- this function should return `Result` or `Option` to accept `?`
...
20 |     let val = fasteval2::eval_compiled!(compiled, &slab, &mut map);
   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot use the `?` operator in a function that returns `()`
   |
   = help: the trait `FromResidual<Result<Infallible, fasteval2::Error>>` is not implemented for `()`
   = note: this error originates in the macro `fasteval2::eval_compiled` (in Nightly builds, run with -Z macro-backtrace for more info)

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