To reproduce: use a fire starter to create a charcoal forge from a charcoal pile without crouching. On the forge lighting, client disconnects from the server to a "NoSuchElementException: No value present" screen. From what I can tell, the issue is that the player right clicks the charcoal forge block before the block entity is created. This does not occur with flint and steel because the simple right click action doesn't allow you to instantaneously right click on the new forge, and it doesn't occur if you sneak because shift+rclick doesn't open inventories.