test: minor changes (coding style)

test/common/mixin.hpp

@@ -20,7 +20,7 @@ public:
     using Type::Type;
 
     void bind(entt::any value) noexcept override {
-        if(auto *owner = entt::any_cast<registry_type>(&value)) {
+        if(auto *owner = entt::any_cast<registry_type>(&value); owner) {
             owner->template storage<int>();
         }
     }