Always use .exec() for .find*() and .update() (#8361)

* add exec where missing in /models

* ix taskManager query

* fix top-level controllers

* fix api-v3 controllers

website/server/libs/taskManager.js

@@ -107,6 +107,8 @@ export async function getTasks (req, res, options = {}) {
   } = options;
 
   let query = {userId: user._id};
+  let limit;
+  let sort;
   let owner = group || challenge || user;
 
   if (challenge) {
@@ -122,18 +124,21 @@ export async function getTasks (req, res, options = {}) {
       query.completed = false; // Exclude completed todos
       query.type = 'todo';
     } else if (type === 'completedTodos' || type === '_allCompletedTodos') { // _allCompletedTodos is currently in BETA and is likely to be removed in future
-      let limit = 30;
+      limit = 30;
 
       if (type === '_allCompletedTodos') {
         limit = 0; // no limit
       }
-      query = Tasks.Task.find({
+
+      query = {
         userId: user._id,
         type: 'todo',
         completed: true,
-      }).limit(limit).sort({
+      };
+
+      sort = {
         dateCompleted: -1,
-      });
+      };
     } else {
       query.type = type.slice(0, -1); // removing the final "s"
     }
@@ -144,7 +149,11 @@ export async function getTasks (req, res, options = {}) {
     ];
   }
 
-  let tasks = await Tasks.Task.find(query).exec();
+  let mQuery = Tasks.Task.find(query);
+  if (limit) mQuery.limit(limit);
+  if (sort) mQuery.sort(sort);
+
+  let tasks = await mQuery.exec();
 
   // Order tasks based on tasksOrder
   if (type && type !== 'completedTodos' && type !== '_allCompletedTodos') {