Unable to process Potentiometers content

[raspberrypilearningbot]

There is a markdown issue in step Potentiometers in locale: en. Error: no implicit conversion of nil into String

For mapping values are not allowed in this context errors, the reported line number may be misleading (due to ruby/psych#190).

Check any YAML (eg. in your ---code--- blocks) as missing colons, or a missing space after a colon, are common issues.

Try pasting the YAML into this linter if you're stuck: http://www.yamllint.com/