Fix onlydeltan case on build error page (#1578)

This PR fixes an issue on `viewBuildError.php` where the negative delta
case was broken.

app/Http/Controllers/BuildController.php

@@ -629,7 +629,7 @@ public function apiViewBuildError(): JsonResponse
                     'stderr' => $resolvedBuildFailure['stderror'],
                     'stderrorrows' => min(10, substr_count($resolvedBuildFailure['stderror'], "\n") + 1),
                     'stdoutput' => $resolvedBuildFailure['stdoutput'],
-                    'stdoutputrows' => min(10, substr_count($resolvedBuildFailure['stdoutputrows'], "\n") + 1),
+                    'stdoutputrows' => min(10, substr_count($resolvedBuildFailure['stdoutput'], "\n") + 1),
                 ));
 
                 $this->addErrorResponse($marshaledResolvedBuildFailure, $response);