Opt out of Steam beta client to fix TF2 crash on server join

[Tek7]

If your TF2 client is crashing any time you join a server, opt out of the Steam beta client, restart Steam, and try again.

You can opt out by right-clicking the Steam icon in your system tray, clicking Settings, and clicking Change in the Beta participation section.

Credit goes to reddit user IK-Chris, who posted the solution in this thread:

https://www.reddit.com/r/tf2/comments/nk9ray