Is there a way to retrieve the merge fields of a specific Lightning Email Template in Apex?

I.E.

template.getMergeFields();

I would like to validate the merge fields so that an email is not sent out with empty fields, as is the current behavior.

The EmailTemplate docs do not seem to discuss this.

Is there a way to retrieve the merge fields of a specific Lightning Email Template in Apex?

Example

EmailTemplate template = new EmailTemplate();
template.getMergeFields();

I would like to validate the merge fields so that an email is not sent out with empty fields, as is the current behavior.

The EmailTemplate docs do not seem to discuss this.