E2 visa extension, current visa expiring

Hi, this is the first time this is happening so I was wondering if anyone else had the same experience and could let me know what happened in their situation.

Basically i had a lapse in brain cells in feb and applied for my E2 extension with a passport that expired in august, I got a new passport AFTER i applied for my visa (literally i dont know what i was thinking) - so this caused them to only extend it for 6 months. They told me I couldnt apply for it until 4 months prior to expiration but then I couldn't apply because I was leaving the country for a long summer vacation, which brings us to right now; I'm back in Korea and applying online because there are no more in person appts and my visa expires in 5 weeks - my work will not give me my document needed for online extension, and i dont know how long theyre gonna make me wait.

so.. if my current visa expires before my application is approved... what happens with everything? Im assuming I can stay in the country while its pending, but what about health insurance?? Do I need to go to an office to re apply?

sry for the long post, tbh my visa stuff has been easy before this point so I've never dealt with any hiccups and im just not sure what happens if ur current visa expires while extending. TIA