function hint_for_supported_files(key, ext = '.js') {
	const supported_files = [];

	if (valid_layout_exports.has(key)) {
		supported_files.push(`+layout${ext}`);
	}

	if (valid_page_exports.has(key)) {
		supported_files.push(`+page${ext}`);
	}

	if (valid_layout_server_exports.has(key)) {
		supported_files.push(`+layout.server${ext}`);
	}

	if (valid_page_server_exports.has(key)) {
		supported_files.push(`+page.server${ext}`);
	}

	if (valid_server_exports.has(key)) {
		supported_files.push(`+server${ext}`);
	}

	if (supported_files.length > 0) {
		return `'${key}' is a valid export in ${supported_files.slice(0, -1).join(', ')}${
			supported_files.length > 1 ? ' or ' : ''
		}${supported_files.at(-1)}`;
	}
}
@param {string} key
@param {string} ext
@returns {string | void}