Show invalid url error on UI, add test case

tests/configs/modules/newsfeed/default.js

@@ -3,8 +3,7 @@
  * By Rodrigo Ramírez Norambuena https://rodrigoramirez.com
  * MIT Licensed.
  */
-
-var config = {
+let config = {
 	port: 8080,
 	ipWhitelist: ["127.0.0.1", "::ffff:127.0.0.1", "::1"],
 

tests/configs/modules/newsfeed/incorrect_url.js

@@ -0,0 +1,38 @@
+/* Magic Mirror Test config newsfeed module
+ *
+ * MIT Licensed.
+ */
+let config = {
+	port: 8080,
+	ipWhitelist: ["127.0.0.1", "::ffff:127.0.0.1", "::1"],
+
+	language: "en",
+	timeFormat: 12,
+	units: "metric",
+	electronOptions: {
+		webPreferences: {
+			nodeIntegration: true,
+			enableRemoteModule: true
+		}
+	},
+
+	modules: [
+		{
+			module: "newsfeed",
+			position: "bottom_bar",
+			config: {
+				feeds: [
+					{
+						title: "Incorrect Url",
+						url: "this is not a valid url"
+					}
+				]
+			}
+		}
+	]
+};
+
+/*************** DO NOT EDIT THE LINE BELOW ***************/
+if (typeof module !== "undefined") {
+	module.exports = config;
+}