From db5980b438b6bb573b12d394040988dfbbcbb725 Mon Sep 17 00:00:00 2001
From: Fabien Spindler <Fabien.Spindler@inria.fr>
Date: Tue, 8 Oct 2024 09:07:12 +0200
Subject: [PATCH] Fix warning: argument 1 null where non-null expected

---
 modules/core/include/visp3/core/vpIoTools.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/modules/core/include/visp3/core/vpIoTools.h b/modules/core/include/visp3/core/vpIoTools.h
index 6212a57ff8..1ef5371432 100644
--- a/modules/core/include/visp3/core/vpIoTools.h
+++ b/modules/core/include/visp3/core/vpIoTools.h
@@ -316,7 +316,9 @@ template<typename T> void npz_save(std::string zipname, std::string fname, const
   //write everything
   fwrite(&local_header[0], sizeof(char), local_header.size(), fp);
   fwrite(&npy_header[0], sizeof(char), npy_header.size(), fp);
-  fwrite(&data[0], sizeof(T), nels, fp);
+  if (data != nullptr) {
+    fwrite(&data[0], sizeof(T), nels, fp);
+  }
   fwrite(&global_header[0], sizeof(char), global_header.size(), fp);
   fwrite(&footer[0], sizeof(char), footer.size(), fp);
   fclose(fp);