Differnet way to save persistent data

src/main/java/net/miavalley/roughleaderboards/mixin/ModEntityDataSaverMixin.java

@@ -0,0 +1,21 @@
+package net.miavalley.roughleaderboards.mixin;
+
+
+import net.miavalley.roughleaderboards.util.IEntityDataSaver;
+import net.minecraft.entity.Entity;
+import net.minecraft.nbt.NbtCompound;
+import org.spongepowered.asm.mixin.Mixin;
+
+@Mixin(Entity.class)
+public abstract class ModEntityDataSaverMixin implements IEntityDataSaver {
+    private NbtCompound persistentData;
+
+
+    @Override
+    public NbtCompound getPersistentData() {
+        if (this.persistentData == null) {
+            this.persistentData = new NbtCompound();
+        }
+        return persistentData;
+    }
+}

src/main/java/net/miavalley/roughleaderboards/util/IEntityDataSaver.java

@@ -0,0 +1,7 @@
+package net.miavalley.roughleaderboards.util;
+
+import net.minecraft.nbt.NbtCompound;
+
+public interface IEntityDataSaver {
+    NbtCompound getPersistentData();
+}