Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: 1.67.1
• OS Version: Windows_NT x64 10.0.19044

Steps to Reproduce:

1. Enable the drop threshold square code in editorDropTarget.ts by uncommenting it. (Could this be wrapped in a configuration setting instead of just commenting it??)
2. Notice linter complains about possibility of this.overlay being undefined. (Although I don't think it will ever be undefined in this code)
3. Observe two variables are unrecognized. groupViewWidth and groupViewHeight (compilation error here)

This code is currently commented so doesn't effect production, but I would like to update this because I found the debug square to be cool and would like to use it in my development environment. Please let me know if this is the proper way to go about this sort of thing as this is my first time opening an issue. This is very low priority, but I wanted to open a pull request for this so I needed a corresponding issue.