function validate_load_response(data, id) {
	if (data != null && Object.getPrototypeOf(data) !== Object.prototype) {
		throw new Error(
			`a load function in ${id} returned ${
				typeof data !== 'object'
					? `a ${typeof data}`
					: data instanceof Response
						? 'a Response object'
						: Array.isArray(data)
							? 'an array'
							: 'a non-plain object'
			}, but must return a plain object at the top level (i.e. \`return {...}\`)`
		);
	}
}
@param {any} data
@param {string} [id]