Macro define_err_macro 

macro_rules! define_err_macro {
    ($macro_name:ident, $error:ty, $error_type:ty, $doc:expr) => { ... };
}

Internal helper macro that defines an error creation macro.

This avoids using the paste crate and keeps the implementation simple. Each error module should use this to define their own specialized macro.

Examples

// In models/src/error.rs:
define_err_macro!(
    model_err,
    ModelError,
    ModelErrorType,
    "Create a ModelError."
);