Error when selecting "Allow multiple selections" options for Node granular date filter.

The website encountered an unexpected error. Please try again later.
TypeError: Unsupported operand types: string + int in Drupal\custom_view_filters\Plugin\views\filter\NodeGranularDateFilter->queryFilter() (line 225 of modules/contrib/custom_view_filters/src/Plugin/views/filter/NodeGranularDateFilter.php).
Drupal\custom_view_filters\Plugin\views\filter\NodeGranularDateFilter->queryFilter('created', 'A') (Line: 159)
Drupal\custom_view_filters\Plugin\views\filter\NodeGranularDateFilter->query() (Line: 1373)
Drupal\views\ViewExecutable->_build('filter') (Line: 1262)
Drupal\views\ViewExecutable->build() (Line: 392)
Drupal\views\Plugin\views\display\PathPluginBase->execute() (Line: 196)
Drupal\views\Plugin\views\display\Page->execute() (Line: 1630)

Steps to reproduce

• Add Node granular date filter to exposed filter
• Use created in the field name field.
• Check "Allow multiple selections" options.
• Save the view and navigate to views page.

Remaining tasks

User interface changes

API changes

Data model changes