netnet should warn about general errors

[nbriz]

while netnet is being designed to try && catch common JS mistakes + warn users about them w/friendly error messages within the actual editor, i'm thinking that long term (when students start building on basic JS knowledge && start using JS libraries + APIs) it would be helpful if netnet actually introduced them to the actual Web Console.

maybe netnet can catch actual console errors:

window.addEventListener('error', (err) => {
  // do something with err object
})

and then create some sort of dialogue with the student, prompting them to open their Web Console and explaining how to use it. specifically explaining how to read error messages (ex. how to spot the line number, etc)

[nbriz]

might also want to use something like devtools-detect to avoid showing users the dialogue if the console is already open