custom amount payments

mongoDB.js

@@ -52,9 +52,11 @@ const getDB = new Promise((resolve, reject) => {
 
         let usernamesCache = {}
         DB.getUsernameByIdCache = async (userid)=>{
+            if(!userid) return {};
             if(usernamesCache[userid]) return usernamesCache[userid];
             const _id = new mongo.ObjectID(userid);
             let user = await DB.usersCol.findOne({ _id });
+            if(!user) return '';
             usernamesCache[userid] = user.username;
             return usernamesCache[userid];
         }