Server error when looking at /feed

Hello,
Great plugin, really like it.

I get the following error when accessing the feed using your plugin:
<b>Warning</b>: array_search() expects parameter 2 to be array, string given in <b>/var/www/longtermrentalsmarbella.uk/htdocs/wp-content/plugins/contact-form-submissions/Submissions.php</b> on line <b>136</b>

<b>Fatal error</b>: Cannot unset string offsets in <b>/var/www/longtermrentalsmarbella.uk/htdocs/wp-content/plugins/contact-form-submissions/Submissions.php</b> on line <b>137</b>

I disable your plugin and the error goes away and the feed works.

Any help is appreciated. Thanks in advance.

…Ricardo

https://www.ads-software.com/plugins/contact-form-submissions/