[MC-135039] The game crashes when /setblock-ing a spawner with an entity ID containing capital letters

The bug

When using the following command

/setblock ~ ~ ~ spawner{SpawnData:{id:BIG}}

the server crashes.

It doesn't crash when using the command

/setblock ~ ~ ~ spawner{SpawnData:{id:small}}

Stack trace

18w30b: crash-2018-07-27_12.42.06-server.txt

java.lang.NullPointerException: Exception ticking world
	at axg.g(SourceFile:51)
	at axg.b(SourceFile:197)
	at bjy.a(SourceFile:56)
	at bjy.aa_(SourceFile:74)
	at bjy.Z_(SourceFile:69)
	at tj.a(SourceFile:204)
	at tj.d(SourceFile:180)
	at tk.c(SourceFile:101)
	at tc.a(SourceFile:221)
	at net.minecraft.server.MinecraftServer.b(SourceFile:728)
	at net.minecraft.server.MinecraftServer.a(SourceFile:661)
	at dga.a(SourceFile:159)
	at net.minecraft.server.MinecraftServer.run(SourceFile:564)
	at java.lang.Thread.run(Thread.java:745)