internal/worker: resolve one more panic

Change-Id: Ib8f29d7975b0a3b279dd4a599e7d8f377aa10cd5
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/591116
Auto-Submit: Zvonimir Pavlinovic <zpavlinovic@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Maceo Thompson <maceothompson@google.com>
diff --git a/internal/worker/govulncheck_scan.go b/internal/worker/govulncheck_scan.go
index cd7c48a..c9b7c01 100644
--- a/internal/worker/govulncheck_scan.go
+++ b/internal/worker/govulncheck_scan.go
@@ -482,7 +482,9 @@
 		} else {
 			response, err = s.runGovulncheckScanSandbox(ctx, inputPath, mode)
 		}
-		log.Debugf(ctx, "govulncheck stats: %dkb | %vs", response.Stats.ScanMemory, response.Stats.ScanSeconds)
+		if response != nil {
+			log.Debugf(ctx, "govulncheck stats: %dkb | %vs", response.Stats.ScanMemory, response.Stats.ScanSeconds)
+		}
 		return err
 	})
 	return response, err