Macro format_err 

macro_rules! format_err {
    ($msg:literal $(,)?) => { ... };
    ($field:ident, $msg:ident) => { ... };
    ($field:expr, $($arg:tt)*) => { ... };
}

Macro to format an error.

Arguments

• $msg - The error message.
• $field - The field associated with the error.
• $arg - Additional arguments for the error message.

Returns

An Error instance.