Fix AutocompleteInput erases input while typing

[WiXSL]

Having a AutocompleteInput with an optionText being set to a field that is not of type string throws an internal error

<ReferenceInput
    label={'Product'}
    source={'category_id'}
    reference={'products'}
>

{ /* record:
{ 
    id: 7, // =>  type is number
    name: 'Washed jacket', 
    category_id: 5
}
 */ }
    <AutocompleteInput optionText="id" /> /* While typeing, the input gets cleared */
</ReferenceInput>

This attempts to fix optionText of type string when the data type is not a string but it doesn't when optionText is of type Function.

May be related to #6214