fix Image for non-existing textures in atlas

src/graphics/core/Atlas.cpp

@@ -34,6 +34,14 @@ const UVRegion& Atlas::get(const std::string& name) const {
     return regions.at(name);
 }
 
+std::optional<UVRegion> Atlas::getIf(const std::string& name) const {
+    const auto& found = regions.find(name);
+    if (found == regions.end()) {
+        return std::nullopt;
+    }
+    return found->second;
+}
+
 Texture* Atlas::getTexture() const {
     return texture.get();
 }