Fermented Milk Bucket crashes game upon looking at it with the cursor in inventory.

crash-2020-06-05_12.24.04-client.txt

Unable to reproduce the issue anymore

This is likely a compat issue, because this issue never occurs while using Sandwichable without other mods. I feel like there is a mod you are using that affects item NBT Tags, so it thinks that the tag exists and causes an NPE.