Download / PDF merge: skip leading errors, interpret only 'Could not merge encrypted files'

extension/Classes/Core/Report/Download.php

@@ -188,7 +188,7 @@ class Download {
 
             // Possible output: "Unimplemented Feature: Could not merge encrypted files ('ct.18.06.092-097.pdf')"
             $line = implode(',', $rcOutput);
-            if (false !== strstr($line, "Unimplemented Feature: Could not merge encrypted files (")) {
+            if (false !== ($line = strstr($line, "Unimplemented Feature: Could not merge encrypted files ("))) {
 
                 $arr = explode("'", $line, 3);
                 if (!empty($arr[1]) && file_exists($arr[1])) {