Fix: Collection.cleaned_data prematurely returned values

formset/collection.py

@@ -385,7 +385,7 @@ def cleaned_data(self):
         """
         Return the cleaned data for this collection and nested forms/collections.
         """
-        if not self.is_valid():
+        if self._errors is None or not self.is_valid():
             raise AttributeError(f"'{self.__class__}' object has no attribute 'cleaned_data'")
         if self.has_many:
             return [{name: holder.cleaned_data} for valid_holders in self.valid_holders for name, holder in valid_holders.items()]