Config logo: handle exception

app/scodoc/sco_logos.py

@@ -117,7 +117,11 @@ class Logo:
             os.mkdir(self.dirpath)
 
     def create(self, stream):
+        "enregistre logo"
+        try:
             img_type = guess_image_type(stream)
+        except ValueError as exc:
+            raise ScoValueError("fichier logo invalide") from exc
         if img_type not in scu.LOGOS_IMAGES_ALLOWED_TYPES:
             raise ScoValueError(f"type d'image invalide ({img_type})")
         self._set_format(img_type)