Invalid advancement frame type crashes server

The bug

Specifying an invalid advancement frame type crashes the server when loading the world.

[^crash-2017-05-02_21.19.17-server.txt]

Description: Exception in server tick loop

java.lang.IllegalArgumentException: Unknown frame type 'SOME_INVALID_VALUE'
	at s.a(SourceFile:31)
	at r.a(SourceFile:72)
	at i$a.a(SourceFile:185)
	at my$1.a(SourceFile:52)
	at my$1.deserialize(SourceFile:48)
	at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69)
	at com.google.gson.Gson.fromJson(Gson.java:887)
	at com.google.gson.Gson.fromJson(Gson.java:852)
	at com.google.gson.Gson.fromJson(Gson.java:801)
	at com.google.gson.Gson.fromJson(Gson.java:773)
	at my.d(SourceFile:99)
	at my.a(SourceFile:72)
	at my.<init>(SourceFile:66)
	at nt.b(SourceFile:162)
	at cgc.a(SourceFile:98)
	at cgc.j(SourceFile:130)
	at net.minecraft.server.MinecraftServer.run(SourceFile:436)
	at java.lang.Thread.run(Unknown Source)

How to reproduce

1. Download the attached advancement

1. and place it in the following directory of your world folder

   data\advancements\custom

2. Try to open the world