assetUrl({ runtime, module, codeGenerationResults }) {
		if (!module) {
			return "data:,";
		}
		const codeGen = codeGenerationResults.get(module, runtime);
		const data =
			/** @type {NonNullable<CodeGenerationResult["data"]>} */
			(codeGen.data);
		if (!data) return "data:,";
		const url = data.get("url");
		if (!url || !url["css-url"]) return "data:,";
		return url["css-url"];
	}
@param {object} options options object
@param {Module} options.module the module
@param {RuntimeSpec=} options.runtime runtime
@param {CodeGenerationResults} options.codeGenerationResults the code generation results
@returns {string} the url of the asset