I made a server through minecraft-hosting.pro and I was using command blocks to get my player head and when i pressed the button to get it, my game crashed right away. Everytime I got on the server It crashes right away.

I made a Minecraft server using Minecraft-hosting.pro and I wanted to get the staffs' player heads. I got a command block and I put a button on the command block and then I used the website heads.freshcoal.com to get then command for each of our heads. I used my heads' command as a test and I put the command in the command block. Then, I pressed the button and right when I did that, my game crashed. I tried going back into Minecraft and into the server and right when I connect to it my game crashes right away.