Make saving more user-friendly

[shinytang6]

Before your pull request is reviewed and merged, make sure you

• there are no linting errors -- npm run lint
• code is in uniquely-named feature branch, and has been rebased on top of latest master. If you're asked to make more changes make sure you rebase onto master then too!
• pull request is descriptively named and links to an issue number, i.e. Fixes #123

Thank you! Closes #560 , Fixes #567

[catarak]

not sure if this is the right way to handle this—just added a thought on #560!

[catarak]

i found a weird bug, and here are the steps to reproduce:

1. Open the editor, no logged in (I recommend an incognito window)
2. Open an existing sketch (one of the examples is easiest)
3. Try to save it using command + s. It will tell you to login or signup
4. Login.
5. Try to save it again using command + s. It will properly fork it but then it will also show a modal asking you to login or signup.

This does work if you are already logged in and navigate to a sketch that you do not own!

[shinytang6]

l think it should be a real bug and doesn't matter with my changes because it can be reproduced in current version:)
Just fixed it in this PR and l will report that issue 😶

[catarak]

got it, thanks for fixing it!

[shinytang6]

@catarak It seems there are still some bugs related to that PR.

1. l shouldn't delete the closeOverlay={this.props.hideErrorModal}
2. when you log in normally and save the changes through command/ctrl s, it still pops up the ErrorModal. The problem is that the 'keydown' event is triggered twice in that case:)