Error loading project with optional `packages` field missing in stack.yaml

I have a [Hakyll](https://github.com/jaspervdj/hakyll) project open (repo [here](https://github.com/armatures/blog)), and I've installed this plugin. Syntax highlighting looks good, but I get this error in my "problems" tab:

My `main` is in the root of the project directory, and in my cabal file, I have the line ` main-is: site.hs`, would this be a problem?
Thank you!

Start by reproducing the error in the linked Hakyll project, then compare its stack.yaml and Cabal file, including the main-is entry for site.hs. Trace how the project is loaded and confirm that a project with the optional packages field absent loads without an error in the problems tab.

Written by the indexing model from the issue text.