fix not being able to set blueprints to the construction markers

common/buildcraft/builders/BlockConstructionMarker.java

@@ -80,9 +80,10 @@ public class BlockConstructionMarker extends BlockMarker {
 		} else if (equipped instanceof ItemConstructionMarker) {
 			if (ItemConstructionMarker.linkStarted(entityplayer.getCurrentEquippedItem())) {
 				ItemConstructionMarker.link(entityplayer.getCurrentEquippedItem(), world, x, y, z);
+				return true;
 			}
 		}
 
-		return true;
+		return false;
 	}
 }

common/buildcraft/builders/BlockMarker.java

@@ -97,7 +97,7 @@ public class BlockMarker extends BlockBuildCraft {
 		if (tile instanceof TileMarker) {
 			((TileMarker) tile).tryConnection();
 		}
-		return true;
+		return false;
 	}
 
 	@Override

common/buildcraft/builders/ItemBlueprint.java

@@ -123,6 +123,10 @@ public abstract class ItemBlueprint extends ItemBuildCraft implements IBlueprint
 		}
 
 		LibraryId id = getId(stack);
+		if (id == null) {
+			return null;
+		}
+
 		NBTTagCompound nbt = BuildCraftBuilders.serverDB.load(id);
 		BlueprintBase base;
 		if (((IBlueprintItem) stack.getItem()).getType(stack) == IBlueprintItem.Type.TEMPLATE) {