Restore legacy default allocation behavior in SmartPointer default constructor to fix crashes in tests

src/Core/SmartPointer.h

@@ -56,8 +56,13 @@ public:
 
     /**
      * @brief Default constructor.
+     * Allocates a new T following legacy behavior.
      */
-    SmartPointer() noexcept : m_counter(nullptr) {}
+    SmartPointer() : m_counter(nullptr) {
+        if constexpr (std::is_default_constructible_v<T>) {
+            m_counter = new ReferenceCounter(new T());
+        }
+    }
 
     /**
      * @brief Constructor from nullptr.