I decided to play a laggy adventure map, and eventually I decided to quit. My computer is quite fast and my virus scanner found nothing. Upon exiting, I deleted the world. I checked the launcher console at that time, and saw that it was writing many things to the console. I quit Minecraft at that point, and an error was printed into the console.

[17:37:57] [Client thread/INFO]: Stopping!
//Quit the game
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
[17:37:57] [Server thread/INFO]: [@: Set the display objective in slot 'sidebar' to 'Power']
[17:37:57] [Server thread/INFO]: [@: Changing to clear weather]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
[17:37:57] [Server thread/INFO]: [@: Set the display objective in slot 'sidebar' to 'Power']
//Deleted the world
[17:37:57] [Server thread/INFO]: [@: Changing to clear weather]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
[17:37:57] [Server thread/INFO]: [@: Set the display objective in slot 'sidebar' to 'Power']
[17:37:57] [Server thread/INFO]: [@: Changing to clear weather]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: Block placed]
[17:37:57] [Server thread/INFO]: [@: 10 blocks filled]
//Closing Minecraft
AL lib: (EE) alc_cleanup: 1 device not closed