check against nullptr

include/blt/std/allocator.h

@@ -210,6 +210,8 @@ namespace blt
             
             void deallocate(pointer p, size_t n) noexcept
             {
+                if (p == nullptr)
+                    return;
 //                for (size_t i = 0; i < n; i++)
 //                    p[i].~T();
                 for (auto*& blk : blocks)