Set ocr to failed text to make them easy to find in the manager

class_image.php

@@ -152,6 +152,7 @@ class MTGImage implements JsonSerializable {
           $text = str_replace("\n", " ", $text);
           return $this->setOCR($text);
       } catch ( Exception $e ) {
+          $this->setOCR("ocr failed");
           return $e->getMessage();
       }
    }