Error when using ACF Extended 'Date Range Picker' field

We've had a report of some errors occurring when using ACF Extended's 'Date Range Picker' field in form. The two errors we've seen are as follows:

PHP Warning:  Illegal string offset 'start' in /path/to/acf-extended-pro/pro/includes/fields/field-date-range-picker.php 

OR

Fatal error: Uncaught TypeError: Cannot access offset of type string on string in /path/to/acf-extended-pro/pro/includes/fields/field-date-range-picker.php

These errors occur on form submission and the reason it happens is because in Advanced Forms, we format all submitted values using ACF's acf_format_value() function as part of the submission. This is so formatted values can then be used in email notifications, success messages, etc. 

After some digging, I was able to reproduce the issue with ACF Extended's forms when rendering the formatted field value in an ACFE form success message, indicating that this is a possible bug in the field type's format handler. 

A simple workaround for this is to short-circuit the field format handler of that type if/when a string is passed in. You can do so with the following snippet: 

<?php 

add_filter( 'acf/pre_format_value', function ( $null, $value, $post_id, $field ) {
  
  if ( $field['type'] === 'acfe_date_range_picker' and is_string( $value ) ) {
    return $value;
  }

  return $null;
  
}, 10, 4 );