title: Wagtailstreamforms TypeError from_db_value() missing 1 required positional argument: 'context'
body: <p>I got this error when trying to use wagtailstreamforms. Built a from-scratch environment and reproduced the error. The only things I installed:</p>
  
  <pre><code>Django==3.0.5
  wagtail==2.8
  wagtailstreamforms==3.9
  </code></pre>
  
  <p>In base.py added (as prescribed in docs):</p>
  
  <pre><code>    'wagtail.contrib.modeladmin',
      'wagtailstreamforms'
  </code></pre>
  
  <p>Left everything else untouched (standard Wagtail base.py), migrated database. Home page 127.0.0.1:8000 gives Wagtail's welcome page as expected, admin is at 127.0.0.1:8000/admin/ with Streamforms item in menu on the left as expected. When I click on it, I can make a form and when I make the first field for the form and then save it, I get the error above. After that I cannot access the Streamforms section anymore, I immediately get the same error when I try.</p>
  
  <p>I looked through all posts on SO on wagtailstreamforms and many similar items on the internet, no solution. What am I doing wrong?</p>
  
  <p>Complete error log:</p>
  
  <pre><code>Internal Server Error: /admin/wagtailstreamforms/form/
  Traceback (most recent call last):
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/core/handlers/exception.py", line 34, in inner
      response = get_response(request)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/core/handlers/base.py", line 145, in _get_response
      response = self.process_exception_by_middleware(e, request)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/core/handlers/base.py", line 143, in _get_response
      response = response.render()
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/response.py", line 105, in render
      self.content = self.rendered_content
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/response.py", line 83, in rendered_content
      return template.render(context, self._request)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/backends/django.py", line 61, in render
      return self.template.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 171, in render
      return self._render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
      return compiled_parent._render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
      return compiled_parent._render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
      return compiled_parent._render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/defaulttags.py", line 309, in render
      return nodelist.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 936, in render
      bit = node.render_annotated(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/base.py", line 903, in render_annotated
      return self.render(context)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/template/library.py", line 214, in render
      _dict = self.func(*resolved_args, **resolved_kwargs)
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/wagtail/contrib/modeladmin/templatetags/modeladmin_tags.py", line 94, in result_list
      'results': list(results(view, object_list))})
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/wagtail/contrib/modeladmin/templatetags/modeladmin_tags.py", line 74, in results
      for item in object_list:
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/db/models/query.py", line 276, in __iter__
      self._fetch_all()
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/db/models/query.py", line 1261, in _fetch_all
      self._result_cache = list(self._iterable_class(self))
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/db/models/query.py", line 74, in __iter__
      for row in compiler.results_iter(results):
    File "/Users/paulsmits/Code/MyCompany/streamformserror/env/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1095, in apply_converters
      value = converter(value, expression, connection)
  TypeError: from_db_value() missing 1 required positional argument: 'context'
  [12/Apr/2020 19:32:19] "GET /admin/wagtailstreamforms/form/ HTTP/1.1" 500 304823
  </code></pre>