Fixed valid block check to not include items

src/main/java/com/sk89q/worldedit/bukkit/BukkitWorld.java

@@ -87,6 +87,7 @@ public class BukkitWorld extends LocalWorld {
     private World world;
     private boolean skipNmsAccess = false;
     private boolean skipNmsSafeSet = false;
+    private boolean skipNmsValidBlockCheck = false;
 
     /**
      * Construct the object.
@@ -866,7 +867,15 @@ public class BukkitWorld extends LocalWorld {
      */
     @Override
     public boolean isValidBlockType(int type) {
-        return type <= 4095 && Material.getMaterial(type) != null;
+        if (!skipNmsValidBlockCheck) {
+            try {
+                return type >=0 && type < net.minecraft.server.Block.byId.length
+                        && net.minecraft.server.Block.byId[type] != null;
+            } catch (Exception e) {
+                logger.log(Level.SEVERE, "Error checking NMS valid block type", e);
+            }
+        }
+        return Material.getMaterial(type) != null && Material.getMaterial(type).isBlock();
     }
 
     @Override