ignore the error on this line - we know that fetcher has getCacheKey …

…method

src/FetchAuthTokenCache.php

@@ -327,7 +327,7 @@ private function saveAuthTokenInCache($authToken, $authUri = null)
 
     private function getCachedUniverseDomain(GetUniverseDomainInterface $fetcher): string
     {
-        $cacheKey = $this->getFullCacheKey($fetcher->getCacheKey() . 'universe_domain');
+        $cacheKey = $this->getFullCacheKey($fetcher->getCacheKey() . 'universe_domain'); // @phpstan-ignore-line
         if ($universeDomain = $this->getCachedValue($cacheKey)) {
             return $universeDomain;
         }