TypeError: 'NoneType' object has no attribute '__getitem__'

[kfischl]

I am getting this error when I run the below file:

Starting nengo server accessible at:
  http://localhost:8080/?token=edd8e711b8187eb5f7003120f6284e45177c946ddd23acfe
('error processing message', 'u\'{"act":"feedforward_layout","uid":null}\'')
Traceback (most recent call last):
  File "/Applications/anaconda2/lib/python2.7/site-packages/nengo_gui/components/netgraph.py", line 407, in message
    self, **info)
  File "/Applications/anaconda2/lib/python2.7/site-packages/nengo_gui/user_action.py", line 22, in create_action
    return FeedforwardLayout(net_graph, **kwargs)
  File "/Applications/anaconda2/lib/python2.7/site-packages/nengo_gui/user_action.py", line 266, in __init__
    self.scale = self.net_graph.page.config[self.network].size[0]
TypeError: 'NoneType' object has no attribute '__getitem__'

file:

import nengo
import numpy as np

model = nengo.Network()
with model:
    
    # an N dimesional vector with low level features
    # teeth baring, eye contact, facial expression (threatening to passive),
    # tone (from animal you are watching, for humans could be tone of voice - maybe
    # indicates the agressiveness)
    input_stim_dim = 4
    low_stim= nengo.Node([input_stim_dim])
    
    # this is a 2 dimensional value that indicates the current emotional state
    # of this animal, the dimensions correspond to arousal and valence and take 
    # values from [-1,1]
    high_stim= nengo.Node([2])
    
    # a sparse representation of the input
    lateral = nengo.Ensemble(n_neurons=200,dimensions=input_stim_dim)
    
    # this nuclei stores the current emotional state which is two dimension
    # that are arousal and valence as well as the emotional state of the input,
    # as passed into it from the lateral nucleus
    basal = nengo.Ensemble(n_neurons=200,dimensions=4)
    
    # decides the physio reaction to have
    central = nengo.Ensemble(n_neurons=200,dimensions=1)
    
    PFC = nengo.Ensemble(n_neurons=200,dimensions=1)
    
    # an idenity equse repreatation, later maybe doing this sparsely
    nengo.Connection(low_stim,lateral)
    
    # this is also basically an identiy connection
    nengo.Connection(high_stim,PFC)
    
    nengo.Connection(PFC,basal)
    nengo.Connection(basal,PFC)
    
    # this calculates the emotional salency of the input
    # aka is the input scary? or what?
    # it returns the emotional state of the input
    def emotional_sal(t):
        return 0, 0

    # decides saliency - gives the emotional evaulation of what came into the system
    nengo.Connection(lateral, basal, function=emotional_sal)
    
    nengo.Connection(basal,central)
    
    # this connection determines which inputs are immediately important
    nengo.Connection(lateral,central)
    
    # this will be an N dimensional vector with the physiological reactions
    # HR, adreline, breathing rate, sweating
    phy_reaction = nengo.Node(None,size_in=5)
    
    # this is the emotional state 
    emotional_state = nengo.Node(None,size_in=2)
    
    # this function returns the new current emotional state based on the previous
    # emotional state (dims 0-1) and the calculated emotional value of the input (dims 2-3)
    def current_emotional_eval(t):
        return 0,0
    
    nengo.Connection(basal,high_output, function=current_emotional_eval)
    nengo.Connection(central,phy_reaction)