STEPS TO REPRODUCE:
1: Have someone on your network start a LAN Server
2: Select that server in the multiplayer menu (Don't login, just highlight)
3: Press Delete
The game will crash
Possible solution:
Minecraft can tell if its a LAN server. If you highlight a LAN server, you should make it grey out the delete button.
Environment
OS: Windows 7 (ver 6.1, arch x86)
Java: 1.7.0_21 (by Oracle Corporation)
Launcher: 0.9.3 (Dev) (bootstrap 3)
Minecraft: 13w25a (updated Mon Jun 17 07:08:06 MST 2013)
Duplicate of MC-12731, please use the search function to see if your bug has already been submitted. Currently over 57% of tickets are being closed as duplicate.