Handling null in Transfer method

src/DotNetty.Common/ThreadLocalPool.cs

@@ -236,7 +236,7 @@ internal void Add(DefaultHandle handle)
  // transfer as many items as we can from this queue to the stack, returning true if any were transferred
  internal bool Transfer(Stack dst)
  {
- Link head = this.head.link;
+ Link head = this.head?.link;
  if (head == null)
  {
  return false;
@@ -259,6 +259,11 @@ internal bool Transfer(Stack dst)
  return false;
  }
 
+ if (dst?.elements == null)
+ {
+ return false;
+ }
+
  int dstSize = dst.size;
  int expectedCapacity = dstSize + srcSize;
 
@@ -273,9 +278,19 @@ internal bool Transfer(Stack dst)
  DefaultHandle[] srcElems = head.elements;
  DefaultHandle[] dstElems = dst.elements;
  int newDstSize = dstSize;
+ if (head.elements == null)
+ {
+ return false;
+ }
+
  for (int i = srcStart; i < srcEnd; i++)
  {
  DefaultHandle element = srcElems[i];
+ if (element == null)
+ {
+ return false;
+ }
+
  if (element.recycleId == 0)
  {
  element.recycleId = element.lastRecycledId;