I have this tingling sense telling me that the same message could be carried with a bit milder, less explicit wording. You are strongly encouraged to try next time, would you.

All classes come from some super class, you need to lookup ancestors also lookup the RUBY docs, Integer inherits methods from its superclasses.

class numeric has step method

I am new to Ruby - I'd expect the min parameter to be an integer, but the integer class doesn't have a step method. What gives?

https://ruby-doc.org/core-2.5.0/Integer.html