app/webpacker/js/turbo.js
import "@hotwired/turbo";
document.addEventListener("turbo:frame-missing", (event) => {
// don't replace frame contents
event.preventDefault();
// show error message instead
status = event.detail.response.status;
if(status == 401) {
alert(I18n.t("errors.unauthorized.message"));
} else {
alert(I18n.t("errors.general_error.message"));
}
});