Eval hovercard should show evaluation error when eval fails

[kenzieschmoll]

In the current state, the eval card shows and then is quickly removed when the evaluation fails. As a user, I would want to know that the evaluation failed and not just that DevTools is buggy and broken.

When this same evaluation is done on the console, we see the error:

[elliette]

Related: dart-lang/webdev#2009

[annagrin]

Btw in VSCode we just don't show hover cards for failed evals (but do in console eval or a watch window) - otherwise that's too much noise (all the syntax errors would pop up and get sticky when you just move the mouse across the screen)

[elliette]

I'm going to close this as not reproducible, I can't think of an example to try that would cause an evaluation error that wouldn't cause a static error now that the null-safety migration is complete.