NullPointerException while saving leads to unsaved scoreboard

When I save in a world that I created in 1.12, the game output shows an exception:

[10:15:25] [Server thread/INFO]: Saving and pausing game...
[10:15:25] [Server thread/INFO]: Saving chunks for level 'The World of Worldly Worlds???'/overworld
[10:15:25] [Server thread/INFO]: [STDERR]: java.lang.NullPointerException
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnl.a(SourceFile:348)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnl$$Lambda$901/1270486355.accept(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.HashMap$Values.forEach(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnl.a(SourceFile:345)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnl$$Lambda$900/995525662.accept(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.HashMap$ValueSpliterator.forEachRemaining(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.util.stream.ReferencePipeline.forEach(Unknown Source)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnl.i(SourceFile:344)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bnm.b(SourceFile:146)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bkv.a(SourceFile:89)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at bkv.a(SourceFile:75)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at ro.a(SourceFile:914)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at ro.a(SourceFile:866)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at net.minecraft.server.MinecraftServer.a(SourceFile:425)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at cmj.v(SourceFile:142)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at net.minecraft.server.MinecraftServer.run(SourceFile:511)
[10:15:25] [Server thread/INFO]: [STDERR]: 	at java.lang.Thread.run(Unknown Source)

When I reload the world, the scoreboards revert back to what they were when I loaded the world.