My game crashed this morning while creating Refined Storage Patterns. The save was corrupted so I loaded a backup, but the same thing happened again when I created a pattern for a Reinforced Upgrade Kit.
Excuse the fact that I'm playing on my dumpster fire of a laptop

crash-2019-04-27_12.38.49-client.txt

This should be fixed in v0.4.20, your world shouldn't be corrupted once you update