The bug

When opening a world, if the player opens their inventory before the world has fully loaded, the game crashes displaying the message: "The game crashed whilst rendering entity in world"

How to recreate

1. Open the game
2. Select a world and open it (note, the world must be a survival world or a creative world where the last opened tab was the Survival Inventory)
3. Once the world first opens (when the dirt loading screen disappears) open your inventory (spamming the key works)
4. Game closes world and crashes

My best guess is that the game attempts to load the player's model before it's been loaded into the world, ending with a NullPointerException. Notice that the crash does not occur on any other creative mode inventory tabs.

Crash report

1.14.3-pre2: crash-2019-06-07_18.18.46-client.txt

Description: Rendering entity in world

java.lang.NullPointerException: Rendering entity in world
	at dty.a(SourceFile:55)
	at dty.a(SourceFile:34)
	at dpl.a(SourceFile:385)
	at dbm.a(SourceFile:142)
	at dbd.a(SourceFile:770)
	at daq.render(SourceFile:83)
	at dbf.render(SourceFile:42)
	at dbd.render(SourceFile:671)
	at dkn.a(SourceFile:686)
	at cvn.e(SourceFile:954)
	at cvn.b(SourceFile:411)
	at net.minecraft.client.main.Main.main(SourceFile:154)