Hi. I saw this as I started.
An error occured running the Unity content on this page. See your browser's JavaScript console for more info. The error was:
Error: Permission denied to access property "toString"
Thank you for the feedback! I didn't really plan on uploading this because it was basically just a test while I got familiar with Unity. Adding upgrades is definitely something I'd look to add in a full version of the game.
Thanks for the info, GregorinV, it seems this has an impact on a small number of users, but we will investigate.