[6.12.8] if u cant do 2 thigns at same time, just dont allow it?

So i had 2 tabs open and in one of them i triggered the update process to 6.12.9 and in the other tab i removed a plugin, which made a complete mess (like the messages from the plugin show in the update process) in the end, it broke the update process.

So if u cant do these 2 things together, dont allow it. 

Thanks.