Be sure to set initialized flag to false before performing the first allocation.

src/initialize_allocator.c

@@ -83,6 +83,7 @@ void initialize_allocator(allocator_t *allocator) {
     allocator->border_ptr = starting_address;
     allocator->remaining_size = size;
 #endif /* WITH_MEMORY_SPACE_AWARENESS */
+    allocator->initialized = false;
 
 #ifdef WITH_FIXED_LISTS