fes.js/packages/fes-preset-built-in/src/plugins/features/publicPath.js

export default (api) => {
    api.describe({
        key: 'publicPath',
        config: {
            default: '/',
            schema(joi) {
                return joi.string().regex(/\/$/).error(new Error('config.publicPath must end with /.'));
            },
        },
    });
};