LevelDatToSavedDataFileFix.java.patch

--- a/net/minecraft/util/filefix/fixes/LevelDatToSavedDataFileFix.java
+++ b/net/minecraft/util/filefix/fixes/LevelDatToSavedDataFileFix.java
@@ -120,6 +_,12 @@
             return content;
         } else {
             Dynamic<?> playerTag = playerTagOpt.result().get();
+            // Paper start - check if player tag is empty, for avoidance create fallback user file with not data
+            final Boolean emptyPlayerTag = playerTag.convert(net.minecraft.nbt.NbtOps.INSTANCE).getValue().asCompound().map(net.minecraft.nbt.CompoundTag::isEmpty).orElse(true);
+            if (emptyPlayerTag) {
+                return content.remove("Player");
+            }
+            // Paper end
             int dataVersion = NbtUtils.getDataVersion(playerTag);
             Dynamic<?> playerTagFixed = DataFixTypes.PLAYER.update(DataFixers.getDataFixer(), playerTag, dataVersion, this.getVersion());
             Optional<? extends Dynamic<?>> playerUuid = playerTagFixed.get("UUID").result();