[framework] Fix create ImageTypeNotFoundException with null imageType…

… attr (#3334)

Co-authored-by: Milan Staňo <milan.stano@shopsys.com>

src/Component/Image/Config/ImageEntityConfig.php

@@ -61,6 +61,6 @@ public function isMultiple(?string $type): bool
             return $this->multipleByType[$key];
         }
 
-        throw new ImageTypeNotFoundException($this->entityClass, $type);
+        throw new ImageTypeNotFoundException($this->entityClass, $key);
     }
 }