FEATURE: Allow empty feature yaml files

* Handle empty yaml files for features in options class.

src/Standards/Typo3Update/Options.php

@@ -140,10 +140,11 @@ class Options
         );
 
         foreach ($fileNames as $file) {
-            $option = array_merge(
+            $content = Yaml::parse(file_get_contents((string) $file));
-                $option,
+            if ($content === null) {
-                Yaml::parse(file_get_contents((string) $file))
+                $content = [];
-            );
+            }
+            $option = array_merge($option, $content);
         }
 
         return $option;