Store guild when creating reminders

web/static/js/reminder_errors.js

@@ -5,7 +5,7 @@ const reminderErrors = () => {
 }
 
 const guildId = () => {
-    let selected: HTMLElement = document.querySelector(".guildList a.is-active");
+    let selected = document.querySelector(".guildList a.is-active");
     return selected.dataset["guild"];
 }