Mailchimp plugin fails to submit via AJAX

Hi folks, I'm running into a limitation with the mailchimp plugin: it doesn't work with AJAX form submission

I've submitted an issue, but while I'm waiting for a response, I'm wondering if there might be an obvious solution I could implement myself.

When I looked up the error messages I got here on grav discourse, I got the impression it might have to do with composer setup. But as an amateur, that's out of my realm.

Update: I'm a novice, and don't really know what composer is, but I discovered that installing the plugin via the grav gpm causes this issue. However, running composer update resolves the issue. Also, installing the plugin via composer results in no issue. I'm guessing the developer forgot to update something in composer when bumping versions.

That wasn't it. It's that the developer chose not to include vendor dependencies in the repo. I made a fork that includes the necessary files. Also created a pull request in the original repo.