If I turn off the internet before trying to vote, it shows as if I voted with success, something that is definitely not true (I can easily confirm by turning on the internet again and reloading the page).
I also don't know what happens if an error in the server side occurs. Yet, I believe that the result is the same regardless if the request went ok or not.
It should deliver, in some way, the error and, if possible (for example, if no internet or some error on the server that is ok to show), display the error that happened.