[Plugin: ActiveCampaign Subscription Form] 5'000 PHP Error Notices per day

This plugin is producing about 5’000 error notices per day …

PHP Notice: Use of undefined constant curl_init - assumed 'curl_init' in /.../wp-content/plugins/activecampaign-subscription-forms/activecampaign_subscribe.php on line 25

I’m not sure if it is a configuration issue or if a fix is needed.

http://ww.wp.xz.cn/extend/plugins/activecampaign-subscription-forms/