V3169. Suspicious return of a local reference variable which always equals null.

The analyzer detected that the 'return' statement returns a local variable that always equals null. This may happen because of a logical error or when someone forgot to assign a correct value to the variable.

Below is an example of a logical error that causes the 'GetRootNode' method to return 'null':

public Node GetRootNode(Node node)
{
  Node parentNode = node.Parent == null ? node : node.Parent;
  while (parentNode != null)
  {
    parentNode = parentNode.Parent;
  }

  return parentNode;
}

Here the 'while' loop executes until the 'parentNode' variable's value is 'null'. To fix the method's behavior, correct the while loop's expression. Instead of 'parentNode', the expression must compare the 'parentNode.Parent' property to 'null'. Here is the fixed 'GetRootNode' method's code:

public Node GetRootNode(Node node)
{
  Node parentNode = node.Parent == null ? node : node.Parent;
  while (parentNode.Parent != null)
  {
    parentNode = parentNode.Parent;
  }

  return parentNode;
}