communities: prevent errors in type field

type attribute now checks if the value passed is a dict to prevent errors from happening before the value is validated. Now returns a normal validation error if the wrong type of value is passed.

invenio_communities/communities/schema.py

@@ -88,9 +88,11 @@ def clean(self, data, **kwargs):
         Why: We want to allow the output of a Schema dump, to be a valid input
              to a Schema load without causing strange issues.
         """
-        for name, field in self.fields.items():
-            if field.dump_only:
-                data.pop(name, None)
+        value_is_dict = isinstance(data, dict)
+        if value_is_dict:
+            for name, field in self.fields.items():
+                if field.dump_only:
+                    data.pop(name, None)
         return data