As of 18w07b the game seems to crash when attempting to open the creative inventory if the recipe book is left open when exiting the crafting menu. At least one recipe must be unlocked to trigger the crash. This does not appear to affect survival mode.

How to test:
1. Open a world in Snapshot 18w07b
2. Enter creative mode
3. Enter the crafting menu and open the crafting book
3-a. Unlock at least one crafting recipe in the crafting book
4. Exit the crafting menu without closing the crafting book, then attempt to open the inventory.

The crash log is provided below:

Unreported exception thrown!
java.lang.ClassCastException: cby$b cannot be cast to amn
at cda.a(SourceFile:39)
at ccy.f(SourceFile:84)
at ccy.a(SourceFile:73)
at ccx.c(SourceFile:186)
at ccx.a(SourceFile:114)
at ccx.a(SourceFile:78)
at ccg.c(SourceFile:56)
at cau.a(SourceFile:310)
at bxe.a(SourceFile:728)
at bxe.av(SourceFile:1335)
at bxe.m(SourceFile:1220)
at bxe.b(SourceFile:791)
at bxe.a(SourceFile:381)
at net.minecraft.client.main.Main.main(SourceFile:141)