[MC-133098] Loading a world with a corrupted stats file crashes the game

The bug

The server crashes as soon as it tries to read an empty (corrupted) json file in the world folder.

Stack trace

1.13-pre6: crash-2018-07-09_11.34.25-server.txt

java.lang.IllegalStateException: Not a JSON Object: null
	at com.google.gson.JsonElement.getAsJsonObject(JsonElement.java:90)
	at wk.a(SourceFile:82)
	at wk.<init>(SourceFile:48)
	at vl.a(SourceFile:923)
	at tb.<init>(SourceFile:162)
	at vl.g(SourceFile:443)
	at ua.b(SourceFile:113)
	at ua.X_(SourceFile:65)
	at hw.a(SourceFile:238)
	at tx.c(SourceFile:170)
	at net.minecraft.server.MinecraftServer.w(SourceFile:716)
	at net.minecraft.server.MinecraftServer.v(SourceFile:623)
	at dfa.v(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:525)
	at java.lang.Thread.run(Thread.java:748)

Original description

The game crashes right after loading a world. No resourcepacks used, no modifications to the client. Clear 1.13-pre6. World made in 1.13-pre6 and played on for 2 days.

(Since bugtracker doesn't allow files above 10 MB, I uploaded the save data to FramaDrop here: https://framadrop.org/r/K1qotv09j1#zY8rE8xMOvzCXtO7aBsZv1CKHFcQG6gbbBHbXOqS3Gk=)