I recently made a new mod using this one as a dependency. I haven't gotten this to happen myself yet, but a few people have been reporting this crash https://mclo.gs/KvnUAQa

Ask if player who get crash get this in the log when start the game
Manifest downloaded in or Unexpected error occurred while downloading versions manifest
If the second occur, can you ask those who get crash open this?
https://launchermeta.mojang.com/mc/game/version_manifest.json

I've gotten the same crash in the latest 2 updates of AssetMover as well.