Function handler_get

pub fn handler_get<TMsg, TError>(
    path: &str,
    get_endpoints: &HashMap<String, Box<dyn GetEndpoint<TMsg>>>,
    error_unknown_path: fn(_: String) -> TError,
    error_serde_json: fn(_: Error) -> TError,
) -> Result<String, TError>

Обработка GET запроса