If you set the max value of a kit a number between 1 and 9, it will crash the plugin.
I found out that if you change the max value manually in oxide/data/Kits.json to 01 (02,03, etc), it works. You should do some changes in the code that makes that the max value is set to 0 than the chosen number, otherwise, it won't work.

What exactly "crashes" about it?

The whole plugin. It stops working at all.

Okay, so it just stops working. Does it have any errors? Did you check your logs? Do the commands work?

When you do set a max value lower than 9, it keeps working until you try to redeem that ki (only tested in the gui). When you do so, you get some errors at the console and the plugin stops working. I can't send the errors now because I'm not home but if you have everything installed you can reproduce it in less than 5 minutes.

Well i just created a kit called Blue-two and set the max as  8 in chat (you dont create kits in data folder) and i redeemed all 8 kits and then redeemed two other kits with no problems !
Are you creating the kits in chat ? (as prescribed by documents) or are you trying to create them in data folder ?.
I am not using the gui so that could be the answer but I have 20+ kits (mostly for the bots) which includes admin, vip, auto, hunter and standard survival kit,