Fix lint error

Author: Andrew Levine

lib/loader.js

@@ -92,7 +92,7 @@ module.exports = function(content, map) {
 				exportJs = "exports.locals = new Proxy(" + exportJs + "," +
 					"{ get(target, property) { " +
 					"if (typeof target[property] !== 'string' && property !== '__esModule') {" +
-					"console.warn(`Attempted to access non-existent className '${property} on CSS module'`)" +
+					"console.warn('Attempted to access non-existent class name' + property + ' on CSS module')" +
 					"} else { return target[property] }" +
 					"}})";
 			} else {