#[macro_export]
macro_rules! constrain {
    ($n:expr, $type_name:expr $(, $arg:expr )*) => {{
        use crate::ErrorKind;
        use crate::Error;

        let args: &[i64] = &[$($arg),*];
        let (min, max) = match args.len() {
            0 => (0, i64::MAX),
            1 => (0, args[0]),
            2 => (args[0], args[1]),
            _ => return Err(Error::from_kind(ErrorKind::RangeError("Invalid arguments".to_string()))),
        };

        if $n < min || $n > max {
            return Err(Error::from_kind(ErrorKind::RangeError(format!("{} is out of {} valid range", $n, $type_name))));
        }

        Ok($n)
    }};
}

i want to define macro, but it report mismatched types.

this is the details error:

error[E0308]: mismatched types
–> util/src/number.rs:12:25
|
12 | _ => return Err(Error::from_kind(ErrorKind::RangeError(“Invalid arguments”.to_string()))),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected (), found Result<_, Error>
…
30 | assert_eq!(constrain!(10, “example”).unwrap(), 10);
| ————————- in this macro invocation
|
= note: expected unit type ()
found enum std::result::Result<_, Error>
= note: this error originates in the macro constrain (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try rustc --explain E0308.

this it the test code:

assert_eq!(constrain!(10, "example").unwrap(), 10);

how to fix this error?