Fixed a small bug in the Builder->toXml() method.

Author: warrick

Diff for: CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.0.2] - 2019-06-24
+### Fixed
+- Fixed a bug in the `Builder->toXml()` that caused an error when no collection had been added.
+
 ## [0.0.1] - 2019-06-20
 - Add products to an XML feed builder.
 - Render the feed as an array.

Diff for: src/Builder.php

@@ -87,7 +87,7 @@ public function toXml(string $filename = null)
         $this->addVersionNode($root);
         $this->addCreatedNode($root);
 
-        $this->products->toXml($root);
+        $this->products()->toXml($root);
 
         if ($filename) {
             $document->save($filename);