Looking for some coding help

Ok so I'm gonna just go ahead and start by saying I am very very new to coding and have no clue what I'm doing. I have mostly followed tutorials and worked by trial and error but I've managed to hit a huge roadblock.

Essentially, I am trying to get where it says "undefined" to say the letters (genotype) that are linked to whats output as the Markings/Modifiers. I have gotten it to work perfectly for the base coat (the letters already given are what match up to "Tuscan". The problem I have run into is the genotype is thrown out fine if I use the .selectOne thing but as soon as I change it to .selectUnique I encounter issues of it not picking up on the related genotypes. I am specifically trying to use the selectUnique function as it works better for what I am trying to do for the Phenotype section (I am wanting between 1-5 non-repeating options to be thrown) and this has been the way that I have found works best for that.

If anyone can help that would be appreciated! Thanks in advance!

Notes:

• If looking at the code, please ignore the lists named "mm" and "mutations". Those were alternative options that still didnt work the way I wanted for the genotype output but work even better for the phenotype output
• Generator is being made for a HARPG community and is designed to throw out a random horse colour combination