If a version.yaml file contains no array, then treat it as empty - fixes #1104

modules/system/classes/VersionManager.php

@@ -233,6 +233,10 @@ class VersionManager
         $versionFile = $this->getVersionFile($code);
         $versionInfo = Yaml::parseFile($versionFile);
 
+        if (!is_array($versionInfo)) {
+            $versionInfo = [];
+        }
+
         if ($versionInfo) {
             uksort($versionInfo, function ($a, $b) {
                 return version_compare($a, $b);