Background of the issue:
On multiple pages on the website of our customer, there is a PHP warning visible: Warning: Invalid argument supplied for foreach() in /home/forge/kidsandcarrots.nl/wp-content/plugins/gravityforms-multilingual/classes/Notification/Routing.php on line 154. I think it has something to do with WPML/translations but I cannot find any issues. The issue is shown here: hidden link and here hidden link but it isn't shown on the English contact page hidden link. I have updated the translations and plugins.
Symptoms:
Warning: Invalid argument supplied for foreach() in /home/forge/kidsandcarrots.nl/wp-content/plugins/gravityforms-multilingual/classes/Notification/Routing.php on line 154
Questions:
What can be a solution for the PHP warning related to GravityForms Multilingual?
Why is the issue not shown on the English contact page?