MQE-1712: Get Error HTTP response code: 500 when using magentoCLI with command config:sensitive:set

- command.php no longer overwrites potentially useful output with empty output

Author: KevinBKozan

etc/config/command.php

@@ -31,7 +31,10 @@
                 $process->run();
                 $output = $process->getOutput();
                 if (!$process->isSuccessful()) {
-                    $output = $process->getErrorOutput();
+                    $failureOutput = $process->getErrorOutput();
+                    if (!empty($failureOutput)) {
+                        $output = $failureOutput;
+                    }
                 }
                 if (empty($output)) {
                     $output = "CLI did not return output.";