Description:

Adding Users via Federation is not working after Updating from 3.17.1 to 3.18.1.
The error message "invalid user" is given.

Steps to reproduce:

1. Go to Directory
2. Go to External Users
3. Search for Federated User
4. Click on the User to start a room

Expected behavior:

User is added and room created

Actual behavior:

The message "invalid user" is displayed

Server Setup Information:

• Version of Rocket.Chat Server: 3.18.1
• Operating System: Ubuntu 20.04
• Deployment Method: tar
• Number of Running Instances: 2
• DB Replicaset Oplog: yes
• NodeJS Version: v12.22.1
• MongoDB Version: 4.2.14

Client Setup Information

• Desktop App or Browser Version: both/Firefox/Chrome
• Operating System: manjaro/Fedora

Additional context

Debug Log show the following:
Sep 21 12:10:37 laura rocketchat[14765]: server.js:204 Federation ➔ client.error afterCreateDirectRoom => Could not create federated room: TypeError: Cannot read property '0' of undefined
Sep 21 12:10:37 laura rocketchat[14765]: at Object.normalizeUser (app/federation/server/normalizers/user.js:30:16)
Sep 21 12:10:37 laura rocketchat[14765]: at app/federation/server/hooks/afterCreateDirectRoom.js:34:41
Sep 21 12:10:37 laura rocketchat[14765]: at Array.map ()
Sep 21 12:10:37 laura rocketchat[14765]: at app/federation/server/hooks/afterCreateDirectRoom.js:33:51
Sep 21 12:10:37 laura rocketchat[14765]: at /opt/Rocket.Chat/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:40

Since the error occured in the user.js file trying to get the property emails at the following place:
const resource = _.pick(originalResource, '_id', 'username', 'type', 'emails', 'name', 'federation', 'isRemote', 'createdAt', '_updatedAt');
const email = resource.emails[0].address;

I therefore logged via the console the array "resource" and got the following back:

{ _id: 'LdJc2Ad2iNrqtuw3L', username: 'USERNAME_REDACTED' }

There is clearly no email address that can be accessed in this array. But i am not sure why this is not the case as the user has every attribute set in the database.