Continues to ask for offline mode username after reconnecting to the internet

[Lamby777]

Operating System

Windows

Description of bug

So, when you're offline, and you try to play, it'll automatically try to launch in Offline Mode, so it asks for your username, right? If you just realized then that you didn't have internet, and you back out of the menu and try again after connecting, it still asks for your offline mode name. This might seem kinda like an edge case, but it happened to me for something like the 5th time today, so I might as well report it.

Not sure if this is too similar to #4356, but that one's mostly focused on sleep rather than not having connection altogether, so yea.

Steps to reproduce

1. Disconnect from the internet
2. Open MultiMC
3. Launch an instance
4. X out of the popup asking for your offline mode username
5. Connect to internet (don't close MultiMC)
6. Launch the instance again
   (shows same popup)

Suspected cause

Haven't looked at the code, but I'd assume it's checking for internet when you open up MultiMC, and then just remembers that you don't have internet as long as that process is open? Maybe check for internet at launch-time? idk

This issue is unique

• I have searched the issue tracker and did not find an issue describing my bug.