ReferenceInput with a blank SelectInput

[stats]

With a simple self referential setup where a category can be the child of another category using

child_category.parent_id = parent_category.id

The following code results in an error when the SelectInput is left blank.

<ReferenceInput label="Parent" source="parent_id" reference="categories">
  <SelectInput optionText="name"/>
</ReferenceInput>

The error reads

{"errors":[{"extensions":{"path":"$.selectionSet.insert_categories.args.objects","code":"data-exception"},"message":"invalid input syntax for type integer: \"\""}]}

This is because the value passed for parent_id is a blank string.

Ra-data-hasura should see this blank string being passed to an integer field and then remove it from the list of parameters submitted when encountered.

[stats]

I believe the issue can be resolved by adding a similar step in typeAwareKeyValueReducer.js that is used for a date field for the Int type.

The problem is that this results in an MUI warning

You have provided an out-of-range value `null` for the select (name="[int field]") component.
Consider providing a value that matches one of the available options or ''.

Is there a better location to change the variable type that would not result in this error?