The warning is related to a Push Notification add-on you are using. It has also caused other error messages that I have seen.
I don't know where the spinbox code is coming from, but I'm not sure why there would be a spinbox in the front-end. Maybe it's related to an admin tool you have installed.
Please note that I am still seeing Redis timeout errors in your logs - at least once every few minutes. If you are running in debug mode, then this timeout error could make some things mysteriously not load, like the activity contents or a deferred image. You should try to resolve your timeout issue as it may cause other problems.
However, even using Firefox and with debug mode active on your main wiki index, I was still not able to reproduce this issue as described.