Error in intro-to-spatial-r tutorial

[AnneMTreasure]

Hi @andysouth ,

When running the code for the intro-to-spatial-r tutorial (on a mac):

learnr::run_tutorial("intro-to-spatial-r", "afrilearnr")

I get the following message:

Listening on http://127.0.0.1:4651
Warning: Error in if: argument is of length zero
  72: ui

and this opens in a browser window: