fix item null or AIR...

Signed-off-by: j502647092 <jtb1@163.com>

src/main/java/cn/citycraft/ProtectItem/utils/ItemManager.java

@@ -4,6 +4,7 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 
+import org.bukkit.Material;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 
@@ -51,6 +52,9 @@ public class ItemManager {
 	}
 
 	public boolean canAction(final ItemStack i, final ActionType action) {
+		if (i == null || i.getType() == Material.AIR) {
+			return true;
+		}
 		final String itemname = getItemName(i);
 		final List<ActionType> actlist = itemlist.get(itemname);
 		if (actlist == null) {