Enabled copper ore mining using wooden tools

src/main/java/jayceecreates/earlygame/mixin/CopperMiningMixin.java

@@ -0,0 +1,50 @@
+package jayceecreates.earlygame.mixin;
+
+import net.minecraft.block.BlockState;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.player.PlayerInventory;
+import net.minecraft.item.*;
+import net.minecraft.world.World;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+import net.minecraft.item.Item;
+import net.minecraft.util.registry.Registry;
+
+// Thanks to Snowdaw#3874 from the Fabric Discord server for the help!
+
+@Mixin(PlayerEntity.class)
+public abstract class CopperMiningMixin extends LivingEntity {
+
+    @Shadow @Final
+    private PlayerInventory inventory;
+
+    @Inject(
+        method = "canHarvest(Lnet/minecraft/block/BlockState;)Z",
+        at = @At("HEAD"),
+        cancellable = true
+    )
+    private void canHarvest(BlockState state, CallbackInfoReturnable < Boolean > cir) {
+        Item heldItem = this.inventory.getMainHandStack().getItem();
+
+        if (heldItem instanceof ToolItem) {
+            int miningLevel = ((ToolItem) heldItem).getMaterial().getMiningLevel();
+            String blockName = Registry.BLOCK.getId(state.getBlock()).toString();
+
+            if (heldItem instanceof PickaxeItem)
+                if (miningLevel == 0 && blockName.equals("minecraft:copper_ore"))
+                    cir.setReturnValue(true);
+        }
+    }
+
+    protected CopperMiningMixin(EntityType<? extends LivingEntity> entityType, World world) {
+        super(entityType, world);
+    }
+
+}

src/main/resources/earlygame.mixins.json

@@ -2,9 +2,10 @@
     "required": true,
     "minVersion": "0.8",
     "package": "jayceecreates.earlygame.mixin",
-    "compatibilityLevel": "JAVA_8",
+    "compatibilityLevel": "JAVA_16",
     "mixins": [
         "BlockMiningMixin",
+        "CopperMiningMixin",
         "IngredientMixin",
         "MatchingStackAccessor",
         "RecipeFieldAccessor"