Fatal Error: Call to undefined function

Using v1.2.0, this plugin is triggering a Fatal Error for a call to an undefined function – specifically in its integration with Ninja Forms.

Fatal Error: Call to undefined function ninja_forms_register_field() in wp-recaptcha-integration/inc/class-wp_recaptcha_ninjaforms.php on line 97

This has previously been mentioned in the following thread, over a year ago:
https://www.ads-software.com/support/topic/ninja-forms-3-0-6-are-giving-error-500-with-wp-recaptcha-integration-1-1-10/

Further, Ninja Forms now includes a bundled reCAPTCHA field, so this integration could be deprecated.