allow serializing empty shared_ptr

1 files changed, 12 insertions, 5 deletions

diff --git a/serialize/tile-atlas.cpp b/serialize/tile-atlas.cpp
index d5350851..fcbb371d 100644
--- a/serialize/tile-atlas.cpp
+++ b/serialize/tile-atlas.cpp
@@ -15,16 +15,23 @@ using proxy_atlas = std::tuple<std::string, Vector2ub>;
 
 void adl_serializer<std::shared_ptr<tile_atlas>>::to_json(json& j, const std::shared_ptr<const tile_atlas>& x)
 {
-    fm_assert(x);
     using nlohmann::to_json;
-    to_json(j, proxy_atlas{x->name(), x->num_tiles2()});
+    if (!x)
+        j = nullptr;
+    else
+        to_json(j, proxy_atlas{x->name(), x->num_tiles2()});
 }
 
 void adl_serializer<std::shared_ptr<tile_atlas>>::from_json(const json& j, std::shared_ptr<tile_atlas>& x)
 {
-    proxy_atlas proxy = j;
-    const auto& [name, num_tiles] = proxy;
-    x = loader.tile_atlas(name, num_tiles);
+    if (j.is_null())
+        x = nullptr;
+    else
+    {
+        proxy_atlas proxy = j;
+        const auto& [name, num_tiles] = proxy;
+        x = loader.tile_atlas(name, num_tiles);
+    }
 }
 
 } // namespace nlohmann