Returning a function doesn't seem to work as expected

[JeremyLT]

I added spoiler tags to your post. For what it’s worth, the guide post for this challenge also has some pretty good solutions that I think are worth looking at.

freeCodeCamp Challenge Guide: Arguments Optional

Arguments Optional Problem Explanation It can be quite complicated to understand what needs to be done. There are always many ways to do something when coding but regardless of the algorithm used, we have to create a program that does the following: It has to add two numbers passed as parameters and return the sum. It has to check if any of the numbers are actual numbers, otherwise return undefined and stop the program right there. It has to check if it has one or two arguments passed. Mor…