Stat weight simulaton, Multiple problems including system/server error and Object reference not set to an instance of Object

https://www.askmrrobot.com/wow/simulator/report/ca6486d92977469196edbac7e9f00fc8

Link to the sim. I had to reload it a few times due to at first either system or server error, it told me to restart it. Then eventually just left me with one or the other, red text, but nothing to do about it. Eventually it completed, but above the status: Completed was Error. in red. When I refreshed the sim, instead of progress it said Object reference not set to an instance of an object.