Handling errors during `connectedCallback`

[PChambino]

Mostly due to bad flags but we could just wrap the whole connectedCallback in a try catch statement since it calls mapFlags and setupPorts, then we could have an onConnectedError function that gets called so we can alert about the component not initialising to an error tracking service e.g. bugsnag.

(These errors do get tracked by a catch all client, but usually these catch all errors are quite noisy so we separate them from high priority JS errors.)

Hopefully that made sense, I will start a PR at some point (🤞) but decided to start with an issue where we can discuss the idea first.