async fn create_initial_const_file(&self, locale: &str) -> Result<(), ServerError> {
        let js_file = self.initial_consts_js(locale).await?;
        self.immutable_store
            .write(
                &if locale.is_empty() {
                    "exported/.perseus/initial_consts.js".to_string()
                } else {
                    format!("exported/.perseus/initial_consts/{}.js", &locale)
                },
                &js_file,
            )
            .await?;

        Ok(())
    }
Creates a JS file to hold the render configuration and the translations,
to avoid putting too much stuff in the initial HTML file (this
enables generally faster page loads, especially for large sites).
packages/perseus/src/turbine/export.rs