Describe the bug
A clear and concise description of what the bug is.
Placing the Magic mirror causes an immediate crash to the client, however the server operates normally and does not crash. client will continue to crash on re-join.
Crash report
ps://pastebin.com/tBtSUbQh
To Reproduce
If applicable, the steps to reproduce the behavior:

1. Place Mirror
2. Look at Mirror

Please complete the following information:

• Minecraft Version: 1.12.2
• Mod Version: cfm-6.2.0-mc1.12.2

I had same problem one year ago without need to watch in a mirror, looking at logs discovered crash were caused by error on mirror sites, had to eliminate all it. Since that day haven't put a single mirror.

Closing since I won't be maintaining 1.12.2 anymore.