warnOnce package in Refine source code.

if (action && action !== "list") {

    const key = `actions.${action}`;

    const actionLabel = translate(key);

    if (typeof i18nProvider !== "undefined" && actionLabel === key) {

      warnOnce(

        true,

        `[useBreadcrumb]: Breadcrumb missing translate key for the "${action}" action. Please add "actions.${action}" key to your translation file.\nFor more information, see https://refine.dev/docs/api-reference/core/hooks/useBreadcrumb/#i18n-support`,

      );

      breadcrumbs.push({

        label: translate(

          `buttons.${action}`,

          textTransformers.humanize(action),

        ),

      });

    } else {

      breadcrumbs.push({

        label: translate(key, textTransformers.humanize(action)),

      });

    }

  }