http://www.pcgamer.com/destiny-2-pc-beta-launch-hit-by-the-saxophone-bug/

The Destiny 2 early access PC beta is now underway! Some of you might be experiencing some issues trying to launch the game, however, specifically in the form of the "Saxophone" errors. But take heart: Bungie is aware of the problem, and it's working on it. 

If you're hit with the error, you'll need to restart Battle.net and then try launching Destiny 2 again, though in our experience you'll simply encounter the same issue.