- Prevent call to Item#initializeClient when in datagen (#8097)  When running under data-generation, the Minecraft singleton is unavailable even though the operating env is under the CLIENT dist. Adding this check prevents crashes from devs unaware of this, as most uses of IItemRenderProperties (usually for a custom BEWLR) make use of the Minecraft singleton and therefore will cause NPEs if not guarded against.  A similar thing happens in MobEffect and Block.