Email Forms Bug

I have the settings to add users to our mail chimp list during registration. but it throw this error:

Warning: array_key_exists() expects parameter 2 to be array, boolean given in /srv/users/serverpilot/apps/intfan/public/wp-content/plugins/tco-email-forms/email-mailchimp/functions/provider.php on line 395

Warning: Cannot modify header information - headers already sent by (output started at /srv/users/serverpilot/apps/intfan/public/wp-content/plugins/tco-email-forms/email-mailchimp/functions/provider.php:395) in /srv/users/serverpilot/apps/intfan/public/wp-includes/pluggable.php on line 1210

Hello There,

Thanks for writing in! This is just a PHP warning message. Usually appears when a variable were not yet initialized. To eliminate this, please disable the debug mode. You can do this by opening wp-config.php and adding
define( 'WP_DEBUG' , true ); just above /* That's all, stop editing! Happy blogging. */

For example:

define('WP_DEBUG', true);

/* That's all, stop editing! Happy blogging. */

When you revisit the page, you should no longer be seeing the message.

Please let us know how it goes.