[MC-251455] Placing Jigsaw Block crashes game

Description

Starting with version 22w18a, placing a Jigsaw Block will crash the game. Loading a world with a placed Jigsaw Block will not (e.g. loading the world that just crashed will not immediately crash again).

Expected Result

The game does not crash when the Jigsaw Block is placed.

Steps To Reproduce

Load or create any world with cheats enabled
Use /give @p minecraft:jigsaw
Place the Jigsaw Block

The world will now freeze as it saves and the game shuts down, coughing up the following report:

Report (system information excluded)

---- Minecraft Crash Report ----
Description: Unexpected error
aa: Non [a-z0-9_.-] character in namespace of location: ResourceKey[minecraft:worldgen/template_pool / minecraft:empty]
    at zy.<init>(SourceFile:38)
    at zy.<init>(SourceFile:46)
    at csc.a(SourceFile:122)
    at esf.a(SourceFile:1083)
    at java.base/java.util.Optional.ifPresent(Optional.java:178)
    at esf.a(SourceFile:1080)
    at ss.a(SourceFile:49)
    at ss.a(SourceFile:14)
    at sj.a(SourceFile:22)
    at axe.d(SourceFile:157)
    at axi.d(SourceFile:23)
    at axe.x(SourceFile:131)
    at axe.bn(SourceFile:116)
    at edr.f(SourceFile:1076)
    at edr.e(SourceFile:728)
    at net.minecraft.client.main.Main.main(SourceFile:237)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
-- Head --
Thread: Render thread
Stacktrace:
    at zy.<init>(SourceFile:38)
    at zy.<init>(SourceFile:46)
    at csc.a(SourceFile:122)
    at esf.a(SourceFile:1083)
    at java.base/java.util.Optional.ifPresent(Optional.java:178)
    at esf.a(SourceFile:1080)
    at ss.a(SourceFile:49)
    at ss.a(SourceFile:14)
    at sj.a(SourceFile:22)
    at axe.d(SourceFile:157)
    at axi.d(SourceFile:23)
    at axe.x(SourceFile:131)
-- Affected level --
Details:
    All players: 1 total; [evq['hdt80br0'/37, l='ClientLevel', x=9.50, y=-60.00, z=0.50]]
    Chunk stats: 729, 461
    Level dimension: minecraft:overworld
    Level spawn location: World: (0,-60,0), Section: (at 0,4,0 in 0,-4,0; chunk contains blocks 0,-64,0 to 15,319,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,-64,0 to 511,319,511)
    Level time: 315 game time, 315 day time
    Server brand: vanilla
    Server type: Integrated singleplayer server
Stacktrace:
    at ese.a(SourceFile:453)
    at edr.d(SourceFile:2277)
    at edr.e(SourceFile:752)
    at net.minecraft.client.main.Main.main(SourceFile:237)
-- Last reload --
Details:
    Reload number: 1
    Reload reason: initial
    Finished: Yes
    Packs: Default

This is very likely the same underlying issue as was in ~~MC-251316~~, ~~MC-139376~~, and ~~MC-154668~~.