Validate user isn't in group before continuing

app/routes/play/index.tsx

@@ -19,6 +19,7 @@ import {
   makeTitle,
   parseRequestFormData,
   requireUser,
+  validate,
 } from "~/utils";
 import * as LFGGroup from "~/models/LFGGroup.server";
 import * as Skill from "~/models/Skill.server";
@@ -51,6 +52,9 @@ export const action: ActionFunction = async ({ request, context }) => {
   });
   const user = requireUser(context);
 
+  const ids = await LFGGroup.activeUserIds();
+  validate(!ids.has(user.id), "Already in an active group");
+
   switch (data._action) {
     case "CREATE_LFG_GROUP": {
       const getRanked = () => {