Hotfix material issue

SpigotCore_8/src/de/steamwar/inventory/SWItem_8.java

@@ -27,7 +27,11 @@ class SWItem_8 {
     private SWItem_8(){}
 
     static Material getMaterial(String material){
-        return Material.valueOf(material);
+        try{
+            return Material.valueOf(material);
+        }catch(IllegalArgumentException e){
+            return Material.STONE;
+        }
     }
 
     static Material getDye(){