Fixed wp-recaptcha error handling in show_recaptcha_in_registration

wp-content/plugins/wp-recaptcha-bp/recaptcha.php

@@ -211,7 +211,9 @@ class ReCAPTCHAPlugin extends WPPlugin
 
         // if it's for wordpress mu, show the errors
         if ($this->is_multi_blog()) {
-            $error = $errors->get_error_message('captcha');
+            if( is_wp_error( $errors ) ) {
+              $error = $errors->get_error_message('captcha');
+            }
             echo '<label for="verification">Verification:</label>';
             echo ($error ? '<p class="error">' . $error . '</p>' : '');
             echo $this->get_recaptcha_html();