Steps

1. Edit a file using the online editor.
2. Click 'Commit'.
3. In the dialog select "Create a pull request for this change". Don't select any reviewers.
4. Click 'Commit'
5. (BUG) UI will look like the attached screenshot. The error is actually: {"type": "error", "error": {"fields": {"reviewers": ["Malformed reviewers list"]}

   , "message": "Bad request"}}. The

6. (BUG) Click commit. You will now get JS errors like:

Uncaught TypeError: this.commit is not a function
    at child.commitChanges (app.js:199800)
    at child.wrapper [as commitChanges] (vendor.js:49138)
    at HTMLDivElement.dispatch (vendor.js:67149)
    at HTMLDivElement.elemData.handle (vendor.js:66835)

You are now in a state:

1. Where it is impossible to commit even if you add a reviewer.
2. The branch has been created with the commit without the PR.

Expected

Either the PR should be created with no reviewers (its possible) or the UI should not allow the commit to be pushed until a reviewer is entered. Also, it should be possible to resolve the problem (e.g. by adding a reviewer) and still create the branch.

It should not be possible to create the branch unless its going to be possible to create the review.