The latest crawling changes allows yourself to hide and crawl inside the composter and cauldron, however, you cannot get out of the composter/cauldron without breaking the block that you're in.

Steps to Reproduce
1. Place a composter/cauldron.
2. Place a trapdoor above it.
3. Open it and go inside the composter/cauldron.
4. Close the trapdoor to get into crawl position inside the composter/cauldron.
5. Look up and try to open the trapdoor in first-person.

Expected Result
You can open the trapdoor.

Observed Result
You can't, you're stuck, unless you have to break the composter/cauldron.