Function load_toml_or_default 

pub async fn load_toml_or_default<T>(path: &Path, what: &str) -> Result<T>
where
    T: DeserializeOwned + Default,

Loads and parses a TOML file at path, or returns T::default() if it doesn’t exist yet. what is a human-readable label used in error messages (e.g. "app manifest").