Update LocalePlugin.php (#1128)

Fix handleQuery() : check if $query->getLocale() is empty!

Author: jbelien

src/Plugin/Plugin/LocalePlugin.php

@@ -41,7 +41,7 @@ public function __construct(string $locale)
     public function handleQuery(Query $query, callable $next, callable $first)
     {
         $locale = $query->getLocale();
-        if (null !== $locale && '' !== $locale) {
+        if (null === $locale || '' === $locale) {
             $query = $query->withLocale($this->locale);
         }