Issue #2671946 by mikeryan: d6_url_alias_language should accept language as a scalar

core/modules/path/migration_templates/d6_url_alias.yml

@@ -19,7 +19,6 @@ process:
       - dst
   langcode:
     plugin: d6_url_alias_language
-    source:
-      - language
+    source: language
 destination:
   plugin: url_alias

core/modules/path/src/Plugin/migrate/process/d6/UrlAliasLanguage.php

@@ -25,8 +25,7 @@ class UrlAliasLanguage extends ProcessPluginBase {
    * {@inheritdoc}
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    $language = reset($value);
-    $langcode = ($language === '') ? LanguageInterface::LANGCODE_NOT_SPECIFIED : $language;
+    $langcode = ($value === '') ? LanguageInterface::LANGCODE_NOT_SPECIFIED : $value;
     return $langcode;
   }