it stop working every time i click "play"

Put the summary of the bug you're having here

What I expected to happen was...:
it happened when i installed the last update of minecraft

What actually happened was...:
when i click on the play button appears a loading bar which at a certain moment disappear and a message pops up saing that there was an unespected error running minecraft, if i open the outputs window while it's opening the game when it send the error message there's a warning that sai's: Skipping bad option: lastServer.

Steps to Reproduce:

• open minecraft
• set on options to see the outputs window
• click play
• wait untill the charging bar disappear and the message pops up