Don't set local close code when remote closes the connection

[abitofevrything]

Description

It seems like some bots are experiencing random disconnections that nyxx is not considering as unexpected (which would cause a reconnect). This means the bot effectively goes offline, but is left in a limbo state where the client is still active.

Im not sure why the reconnect loop isn't triggering. This PR will be updated as I find more problems in the code; for now it only contains a fix the the localCloseCode being set even when Discord closes the connection (causing a race condition of sorts for detecting error close codes).

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• Ran dart analyze or make analyze and fixed all issues
• Ran dart format --set-exit-if-changed -l 160 ./lib or make format and fixed all issues
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works