tree.sv_links.get_nodes(tree)

Created by: Durman

(Pdb) ll
 60     def start_exception_drawing_with_bgl(ng, node_name, error_text, err):
 61         """ start drawing the exception data beside the node """
 62         try:
 63             node = ng.nodes[node_name]
 64         except:
 65             breakpoint()

(Pdb) w
  sverchok\node_tree.py(231)update()
-> self.sv_update()
  sverchok\node_tree.py(104)sv_update()
-> process_from_nodes(self.sv_links.get_nodes(self))
  sverchok\core\update_system.py(484)process_from_nodes()
-> do_update(update_list, ng.nodes)
  sverchok\core\update_system.py(424)do_update()
-> do_update_general(node_list, nodes)
  sverchok\utils\profile.py(104)wrapper()
-> return func(*args, **kwargs)
  sverchok\core\update_system.py(409)do_update_general()
-> start_exception_drawing_with_bgl(ng, node_name, error_text, err)
> sverchok\utils\exception_drawing_with_bgl.py(66)start_exception_drawing_with_bgl()

(Pdb) ll
 95         def sv_update(self):
 96             """
 97             the method checks if anything changed inside the normal tree or monad
 98             and update them if necessary
 99             """
100             self.sv_links.create_new_links(self)
101             if self.sv_links.links_have_changed(self):
102                 self.has_changed = True
103                 build_update_list(self)
104  ->             process_from_nodes(self.sv_links.get_nodes(self))
105                 self.sv_links.store_links_cache(self)
106             else:
107                 process_from_nodes(self.get_groups())
(Pdb) self.sv_links.get_nodes(self)
[bpy.data.node_groups['NodeTree'].nodes["("]]

It means ([bpy.data.node_groups['NodeTree'].nodes["("]]) that the sv_links.get_nodes method sometimes returns objects with invalid link in memory. The question is how to reproduce this.