I started 1.13 via the launcher (2.1.1351) and as soon as the Minecraft window popped up, the game crashed.
The game path I usually use has a hardlink to an external HD for the saves folder that I can play them on multiple devices without the need to manually synchronize. (Didn't do it to the complete .minecraft folder as I play on different OS.) This did work fine with the versions up to 1.12.2. I didn't test it with the snapshots or pre-releases as I don't want my saves to be corrupted, I have a different game path without hard link for the snapshots.
When I made a new profile and changed the game path to something different without an existing hard link, the game started normally. So I guess it's the hard link, and it would be convenient if I could also have my 1.13 saves hardlinked.