The computer is kinda laggy, so this may be a computer issue.
Steps to reproduce:
1. Summon a phantom with size 1000. Command:
/summon minecraft:phantom ~ ~ ~ {Size:1000}
2. The game will crash.
MC-127069
huge phantom crash
Resolved
Fixed
0
No crash, just extreme resource usage and lag that can crash less-than-powerful computers. Kinda like summoning 1000 items would.