The kata needs random tests.

Also, the kata needs chai.config.truncateThreshold = 0.

Discouraging JSON.parse in favour of eval or new Function does not seem like the best idea.

Also, no random tests

Uhm... so this is not a bugfix kata, but there are a whole chunk of solution code as initial code, which also doesn't quite work? It's pretty confusing.

Usually unless it's a bugfix kata, initial solution will only provide the barebone structure for people to fill in the actual code. You might consider deleting the initial code except the function definition.