@schilpat The error isn't handled at all which suggests that this was a typo rather than deliberate way of handling the error... Since it's unhandled.
But please, do tell me more about how deselecting a normal setting in every modern web browser should break the entire website. It's an interesting way of coding I've not heard of before.
Sarcasm aside, there should at least be a message informing users of this, not a complete crash.