In reply to Billy Wilcosky.

I tried out the revised version and the error has gone away.

However, for some reason the posting interface doesn't show up when used with the Twenty Fifteen theme. I've tried a half a dozen other popular themes and didn't see or have any immediate problems. In looking at the source it doesn't seem to be an issue with CSS hiding it. I'm not quite sure where to look to clear up the issue. Ideas?