[MC-249702] Server crash when attempting to start a server with malformatted banned-ips.json

The bug

Attempting to start a server with square brackets missing in banned-ips.json causes a crash.

Stack trace

1.18.2: crash-2022-03-30_19.35.41-server.txt

Description: Exception in server tick loop

java.lang.NullPointerException: Cannot invoke "com.google.gson.JsonArray.iterator()" because "$$1" is null
	at ags.f(SourceFile:121)
	at acw.y(SourceFile:76)
	at acw.<init>(SourceFile:25)
	at acx.e(SourceFile:172)
	at net.minecraft.server.MinecraftServer.w(SourceFile:670)
	at net.minecraft.server.MinecraftServer.a(SourceFile:273)
	at java.base/java.lang.Thread.run(Thread.java:833)

Code analysis

Code analysis by apple502j can be found in this comment.