extensions/css-language-features/server/src/customData.ts/parseCSSData
function parseCSSData(source: string): ICSSDataProvider {
	let rawData: any;

	try {
		rawData = JSON.parse(source);
	} catch (err) {
		return newCSSDataProvider({ version: 1 });
	}

	return newCSSDataProvider({
		version: rawData.version || 1,
		properties: rawData.properties || [],
		atDirectives: rawData.atDirectives || [],
		pseudoClasses: rawData.pseudoClasses || [],
		pseudoElements: rawData.pseudoElements || []
	});
}