strpos error

Hello,

We’ve been receiving this error in our logs:

strpos(): Empty needle

in plugins/sem-external-links/sem-external-links.php on line 727.

I have a proposed fix:

$domain = $this->extract_domain($subdomains);
if(!empty($domain)){
    $subdomains = rtrim( substr($subdomains, 0, strpos($subdomains, $domain)) );
}

However am unsure where/how to contribute.

Can you please advise?

Thanks

https://wordpress.org/plugins/sem-external-links/