[Bug] Empty CustomOAuth sometimes breaks Login.

Description:

An empty (unconfigured) "CustomOAuth" URL breaks the login screen and just shows the user a grey background with three dots.

Steps to reproduce:

1. Install Rocket.Chat the normal way (tarball)
2. Run 0.65.1
3. Have sometimes breakdowns on your clients logins

Expected behavior:

Users would be able to login since custom oAuth is disabled (we just use LDAP)

Actual behavior:

Users get a grey screen with three moving dots (loading/waiting screen)

Server Setup Information:

• Version of Rocket.Chat Server: 0.65.1
• Operating System: CentOS 7.5
• Deployment Method: tar
• Number of Running Instances: 5
• DB Replicaset Oplog: enabled
• NodeJS Version: v8.9.4
• MongoDB Version: 3.4.15

Additional context

-none-

Relevant logs:

Javascript Console Log:

111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:181 Uncaught rdetails: undefinederror: "CustomOAuth: Options.serverURL is required and must be String"errorType: "Meteor.Error"isClientSafe: truemessage: "[CustomOAuth: Options.serverURL is required and must be String]"reason: undefinedstack: "Error: [CustomOAuth: Options.serverURL is required and must be String]↵ at t [as configure] (https://$serverurl$.de/111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:181:1300)↵ at https://$serverurl$.de/111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:443:2096↵ at a (https://$serverurl$.de/111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:9:1322503)↵ at https://$serverurl$.de/111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:9:1321982"proto: Error
111f6dfe3c5b59829f51d2620e189034953def3e.js?meteor_js_resource=true:375 Loading: false