foreach() argument must be of type array|object, null given in workflow_notifications_cron()

Problem/Motivation

Warning: foreach() argument must be of type array|object, null given in workflow_notifications_cron() (line 88 of /app/web/modules/contrib/workflow_notifications/workflow_notifications.module)

Steps to reproduce

Create Drupal installation using workflow_notifications module and do not add any Workflow Notifications of type `before_state_change` -> run cron.

Proposed resolution

Add conditional check for `$result` variable.

User interface changes

None.

API changes

None.

Data model changes

None.