No attribute 'plot_res'

[keflavich]

During stage 2, I got the following error when hitting 'next'.

Traceback (most recent call last):
  File "/orange/adamginsburg/miniconda3/envs/python39/lib/python3.9/site-packages/matplotlib/cbook/__init__.py", line 287, in process
    func(*args, **kwargs)
  File "/orange/adamginsburg/miniconda3/envs/python39/lib/python3.9/site-packages/matplotlib/widgets.py", line 585, in <lambda>
    return self._observers.connect('changed', lambda val: func(val))
  File "/blue/adamginsburg/adamginsburg/repos/scousepy/scousepy/scousefitter.py", line 721, in update_alpha
    update_plot_model(self,update=True)
  File "/blue/adamginsburg/adamginsburg/repos/scousepy/scousepy/scousefitter.py", line 1160, in update_plot_model
    self.plot_res.remove()
AttributeError: 'ScouseFitter' object has no attribute 'plot_res'

When I restarted, it worked, but this error can apparently happen intermittently.