this is null

[ANtlord via Digitalmars-d-learn]

Hello everyone! I've encountered the problem which I already 
encountered before. Unfortunately, I had no time in the previous 
time to report and to talk about it. So I decided to play making 
my own "malloc" function in pure D (betterC) at this time. And I 
encountered the issue one more time. `this` can be null. How? 
Please take a look at my project [0]. It gets the current heap 
break and tries to increase via a free list. So the segfault I 
meet happens there [1]. Tell me, please. What do I wrong?

[0] https://github.com/ANtlord/deadmemory
[1] 
https://github.com/ANtlord/deadmemory/blob/master/src/deadmemory/freelist.d#L56