todo, handle null returns

Author: alyshawang

ddtrace/profiling/collector/_memalloc_heap.c

@@ -407,9 +407,7 @@ memalloc_heap(void)
 
     /* First, iterate over live samples using the new iterator API */
     memalloc_heap_map_iter_t* it = memalloc_heap_map_iter_new(global_heap_tracker.allocs_m);
-    if (it == NULL) {
-        // TODO: return
-    }
+    // TODO: handle NULL return
 
     void* key;
     traceback_t* tb;