Please complete the following information:
Based on ldtteam/minecolonies#8994

Describe the bug
Hi, we've got a crash report caused by our logic, but the problem is that your PlaceholderComponent is implenting just Component iface. I believe that you should switch away from extending component hierarchy in any way. Instead you should create your own ComponentContents class like we do in our mod and use in vanilla MutableComponent. It seems that your PlaceholderComponent is not anyhow special and ComponentContents will do the job.

Sincerely Nightenom

thx