Image uploads fail when /tmp/ufs directory does not exist

Description:

For whatever reason the ufs directory in /tmp was missing. Image uploads fail if that is the case. There is an error message in the browser, but it does only state that a file in /tmp/ufs is missing not that the directory is missing.

Steps to reproduce:

1. cd /tmp; rm -r ufs
2. try to upload an image to a channel in a rocket.chat instance

Expected behavior:

• /tmp/ufs directory is created, then file put there
• error with the information that the directory to upload to does not exist

Actual behavior:

• upload fails
• error message shown states the file /tmp/ufs/ does not exist. (that is technically true but not helpful)

Server Setup Information:

• Version of Rocket.Chat Server: 3.10.2
• Operating System: CentOS 7 (Uberspace)
• Deployment Method: https://lab.uberspace.de/guide_rocketchat.html?highlight=rocket
• Number of Running Instances: 1
• DB Replicaset Oplog:
• NodeJS Version: 12.19.0
• MongoDB Version: db version v4.2.6

Client Setup Information

• Desktop App or Browser Version: Safari 14.0.3
• Operating System: macOS 11

Additional context

Relevant logs:

Browser: [Error] Failed to load resource: the server responded with a status of 400 () (PaMv9AAWxemH7B4Si, line 0) https://regenbogenchat.queer-lexikon.net/api/v1/rooms.upload/PaMv9AAWxemH7B4Si

Server: server log has no entries from today.

Start by reproducing the failure through the /api/v1/rooms.upload endpoint after removing /tmp/ufs. Trace the upload handling and temporary-file path, then make the missing-directory behavior match the expected outcome: create /tmp/ufs before storing the file or report that the upload directory is absent. Confirm the browser error is more informative.