When writing up an application we store a temporary backup of your entered text content locally, in your browser's cache. The main purpose of that functionality is to keep you from losing data if, say, you accidentally close a tab when you were in the middle of creating an application.
Although your browser should clear this cache when you close it, sometimes it doesn't. If the cache gets too full, you'll see an ugly-looking error which says something like, "Browser localStorage is full. Clear storage or increase database size."
The Fix:
Look at the bottom right of the text editor for an icon of a broom. Click that and you'll see an option to delete all the previously stored text. That should resolve your issue! Note that you may have more than one editor box with cached data on the page.
It looks like this:
By the way... to see the cached text, click the downward-facing arrow to the left of the broom.