Strange custom Node error when in update()

Hello there,

In the Update() of a custom node, I try to access the links of this custom node :

if self.outputs: #Success
    for out in node.outputs: #Success
        if out.is_linked: #Success
            for link in out.links: 
                #Error => AttributeError: 'NoneType' object has no attribute 'links'

So “out” is linked but does’nt have any attribute “links” ?
I’m pretty sure this is something like the nodeTree is not properly updated inside the update(). Because when I try the same code from a button it works.

Is there a way to force update a NodeTree or something similar ?
Thank you