Joining a 18w47b server doesn't load the world

What I expected to happen was :
The world should appear when joining a server.

What actually happened was :
There's no world!

Steps to Reproduce:
1. Create a new 18w47b server on localhost
2. Join it
3.

/stop

4. The server will not exit despite being closed. Kill it.
5. Restart the server
6. Join it