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Created by faint on 6/27/2023 in #help
System.NullReferenceException in an if statement
I keep getting System.NullReferenceException directing me to the last if statement in the following code: 
public override IEnumerable<Node> GetReachableNodes(TransformComponent xform, EntityQuery<NodeContainerComponent> nodeQuery, EntityQuery<TransformComponent> xformQuery,
        MapGridComponent? grid, IEntityManager entMan)
    {
        if (grid == null)
            yield break;

        entMan.System<SpreaderSystem>().GetNeighbors(xform.Owner, Name, out _, out _, out var neighbors);

        foreach (var neighbor in neighbors)
        {
            if (!nodeQuery.TryGetComponent(neighbor, out var nodeContainer) ||
                !_nodeContainer.TryGetNode<SpreaderNode>(nodeContainer, Name, out var neighborNode))
            {
                continue;
            }

            yield return neighborNode;
        }
    }
public override IEnumerable<Node> GetReachableNodes(TransformComponent xform, EntityQuery<NodeContainerComponent> nodeQuery, EntityQuery<TransformComponent> xformQuery,
        MapGridComponent? grid, IEntityManager entMan)
    {
        if (grid == null)
            yield break;

        entMan.System<SpreaderSystem>().GetNeighbors(xform.Owner, Name, out _, out _, out var neighbors);

        foreach (var neighbor in neighbors)
        {
            if (!nodeQuery.TryGetComponent(neighbor, out var nodeContainer) ||
                !_nodeContainer.TryGetNode<SpreaderNode>(nodeContainer, Name, out var neighborNode))
            {
                continue;
            }

            yield return neighborNode;
        }
    }
The problem is in _nodeContainer.TryGetNode.... After I moved TryGetNode from one place to another and added a new parameter, that error started appearing. Why does it always appear if all TryGetNode's parameters are nullable: 
        public bool TryGetNode<T>(NodeContainerComponent? component, string? identifier, [NotNullWhen(true)] out T? node) where T : Node
        {
            if (identifier == null || component == null)
            {
                node = null;
                return false;
            }

            if (component.Nodes.TryGetValue(identifier, out var n) && n is T t)
            {
                node = t;
                return true;
            }

            node = null;
            return false;
        }
        public bool TryGetNode<T>(NodeContainerComponent? component, string? identifier, [NotNullWhen(true)] out T? node) where T : Node
        {
            if (identifier == null || component == null)
            {
                node = null;
                return false;
            }

            if (component.Nodes.TryGetValue(identifier, out var n) && n is T t)
            {
                node = t;
                return true;
            }

            node = null;
            return false;
        }
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