How do you print text if a variable doesn't exist?

My goal with this seems simple: if "family" is not a listed value under the random enemy chosen, print "N/A" instead. However, I have zero clue as to how that could be done. I'm looking for a method that would still work well on a larger scale because I plan to apply this fix to this other generator I made: https://perchance.org/pikmin-enemy-generator#edit