r swirl - can't run swirl course, get enigmatic error message

Question

I've created a course using the swirl package in r. The yaml file is created fine.

new_lesson("lesson_name", "course_name")
demo_lesson()

However, I attempt to run the course but get the following error:

Scanner error: mapping values are not allowed in this context at line 61, column 32

This error is incomprehensible to me. Anyone who knows swirl has an idea of what it means, and how to fix it?

Answer 1

Found the error. It was an indentation problem in the yaml document that the swirl() function was using to display the questions. How to find "line 61, column 32" is still mysterious to me, though.