Hidden and non-JS files in /src/components or /src/docs/examples cause "Cannot read property length of undefined" error

When I create a new component directory (with or without the accompanying docs directory), I generate an error after restarting the server.
I expect that after restarting the server, to see the new component listed in the docs page.
Instead I receive the following error.

I can restore the page by removing the new directory and restarting the server. I'm using the configuration files "as is" from this repo.