When R Studio is running the swirl package and the swirl tutorial attempts to open an editor containing a code snippet, the following error is displayed and swirl will exit.

Error in editor(file = file, title = title) :
argument "name" is missing, with no default
| Leaving swirl now. Type swirl() to resume.

Before you restart the swirl tutorial type the following command at the prompt.

options(editor = "internal")
Now when you restart the tutorial the editor will be opened correctly.

Note that if you re-set the R Session (or restart R Studio) you will need to re-run the options command.