Guard against absent 'form_class' kwarg in IETFJSONField.formfield(). Commit ready for merge.

 - Legacy-Id: 19683

Author: jennifer-richards

ietf/utils/db.py

@@ -23,6 +23,6 @@ def __init__(self, *args, empty_values=FormIETFJSONField.empty_values, accepted_
         super().__init__(*args, **kwargs)
 
     def formfield(self, **kwargs):
-        if issubclass(kwargs['form_class'], FormIETFJSONField):
+        if 'form_class' not in kwargs or issubclass(kwargs['form_class'], FormIETFJSONField):
             kwargs.setdefault('empty_values', self.empty_values)
         return super().formfield(**{**kwargs})