Is this referring to the in-page/application UI? (I see this text in some samples.)

If so, there probably isn't much we can do about that. The browser doesn't generally expose localized messages to be displayed to the user. We can provide a more useful message to the developer console, but users are unlikely to look there.

There may also be security/privacy concerns with exposing such a message. If we log to the console, we should log to the secure message that is only available to the user and not to the web app.

Agreed. We can do some console logging to make it more explicit why things failed, but the page should only receive more general error messages regarding page state validation and not browser implementation details.

Fair point. Can we add a help URL in the in-page error? I think we need some place to help user figure out how to fix this issue. Developer console is probably not going to be helpful for most users.

We should work with ConOps to create a Help Center article about this error.  That way when users encounter it, they can search for it and find information on how to fix it.