我很新的编码模式，抱歉，如果这是一个简单的修复。这是日志输出:https://pastebin.com/gnFY6Fa3这是ModItems.java文件

package slimer.mod.init;

import net.minecraft.client.Minecraft;
import net.minecraft.client.resources.model.ModelResourceLocation;
import net.minecraft.item.Item;
import net.minecraftforge.fml.common.registry.GameRegistry;
import slimer.mod.Reference;

public class ModItems {

public static Item copper_ingot; 

public static void init() {
    copper_ingot = new Item().setUnlocalizedName("copper_ingot");
}

public static void register() {
    registerItem(copper_ingot); 
}

public static void registerRenders() {
    registerRender(copper_ingot);   
}

public static void registerItem(Item item) {
    GameRegistry.registerItem(item, item.getUnlocalizedName().substring(5));
    System.out.println("Registered Item: " + item.getUnlocalizedName().substring(5));
}

public static void registerRender(Item item) {
    Minecraft.getMinecraft().getRenderItem().getItemModelMesher().register(item, 0, new ModelResourceLocation(Reference.MODID + ":" + item.getUnlocalizedName().substring(5), "inventory"));
}

}

如果其他文件需要链接，请提前表示感谢

编辑:使用Eclipse进行编辑