implemented PR feedback

Author: oleksandr-pavlyk

dpnp/backend/src/dpnpc_memory_adapter.hpp

@@ -52,7 +52,7 @@ class DPNPC_ptr_adapter final
     bool target_no_queue = false; /**< Indicates that original memory will be accessed from non SYCL environment */
     bool copy_back = false;       /**< If the memory is 'result' it needs to be copied back to original */
     const bool verbose = false;
-    std::vector<sycl::event> deps{};
+    std::vector<sycl::event> deps;
 
 public:
     DPNPC_ptr_adapter() = delete;
@@ -164,10 +164,12 @@ class DPNPC_ptr_adapter final
     }
 
     void depends_on(const std::vector<sycl::event> &new_deps) {
+	assert(allocated);
         deps.insert(std::end(deps), std::begin(new_deps), std::end(new_deps));
     }
 
     void depends_on(const sycl::event &new_dep) {
+	assert(allocated);
         deps.push_back(new_dep);
     }