[MC-159455] Mob riding item frame riding mob crashes the server when item frame breaks

The bug

Summoning a stack of mobs with a mob on bottom, an item frame in the middle, and a mob on top - a bee for example - will crash the game when the item frame breaks.

How to reproduce

Use this command:

/summon wolf ~ ~ ~ {Passengers:[{id:"item_frame",Passengers:[{id:"bee"}]}]}

Wait for the item frame to break
→ Game crashes

Crash report

19w34a: crash-2019-08-22_16.15.31-server.txt

Description: Ticking entity

java.lang.IllegalStateException: Unable to get Y-rotated facing of down
	at fb.e(SourceFile:178)
	at ajx.B(SourceFile:1733)
	at ajx.j(SourceFile:2421)
	at ajo.aa(SourceFile:397)
	at ajx.aa(SourceFile:291)
	at ajy.aa(SourceFile:227)
	at ajo.h(SourceFile:390)
	at ajx.h(SourceFile:2057)
	at ajy.h(SourceFile:294)
	at ata.h(SourceFile:219)
	at ajo.aN(SourceFile:1648)
	at ajx.aN(SourceFile:2427)
	at wj.a(SourceFile:613)
	at wj.a(SourceFile:620)
	at wj.a(SourceFile:591)
	at wj$$Lambda$2703/1685559517.accept(Unknown Source)
	at bit.a(SourceFile:675)
	at wj.a(SourceFile:386)
	at net.minecraft.server.MinecraftServer.b(SourceFile:836)
	at net.minecraft.server.MinecraftServer.a(SourceFile:775)
	at ebt.a(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:643)
	at java.lang.Thread.run(Thread.java:745)