Custom Trades Can Remove Vanilla Items From The Game

When creating an addon that alters or creates new trades that use blocks/items added with the Nether Update, those items will be removed from the creative inventory, give command and all recipes associated with them will break.

The blocks will still appear in natural generation but mining them yields nothing, even with silk touch.

Steps To Reproduce:

1. Download and install attached pack

2. Turn on content log in profile settings

3. Create new world with pack (experimental gameplay can be on or off)

4. As the world generates errors about recipes containing Blackstone should fill the screen

5. When the world loads try and get Blackstone from the creative inventory or a give command, it won't exist.

6. Go to the nether and find a Basalt Deltas or Bastion and Blackstone will be there but mining it will yield nothing.

7. Change Blackstone to another block added in the Nether Update (Crimson Planks, Soul Lantern, Basalt, etc.) and reload, that item will no longer be available but Blackstone will be.

Expected Behavior:

• Custom trades that include blocks/items from the nether update don't remove said block/item from the game

Actual Behavior:

• The block/item included in a trade is unobtainable