utility.guildinfo: null check getGuild return

src/modules/utility.js

@@ -1780,6 +1780,8 @@ guildinfo.callback = async function (msg, line) {
     _guild = await getGuild(line);
   }
 
+  if (!_guild) return "Guild not found.";
+
   const guild = _guild.data;
   switch (_guild.source) {
     case "local": {