Chain of events will make the title clear:
I was reading an answer on Ask Different and upvoted it.
The upvote was shown but a banner came "An error has occurred - please retry your request." I noticed that my Wi-Fi was disconnected.
The upvote arrow is now unresponsive, not letting me remove the vote, nor downvote. Clicking on the vote count also shows another banner with "An error occurred during vote count fetch."
I reconnected Wi-Fi and reloaded the page; the vote count is back to +2.
So shouldn't the vote count be reset to +2 when the "error occurs," instead of erroneously showing +3 in a disconnected state?