fix issue where link url in openUrl function is not defined when clicking on that item will crash the app.

Author: mientjan

src/lib/util/openUrl.js

@@ -1,5 +1,7 @@
 import { Linking } from 'react-native';
 
-export default function openUrl(url){
-	Linking.openURL(url);
-};
+export default function openUrl(url) {
+  if (url) {
+    Linking.openURL(url);
+  }
+}