Simple Lightbox crashes in new version 3.3.6

Hello NGG team,

we just noted a problem with Simple Lightbox in one of our many WordPress installations. It occurs with the newest version of NGG plugin 3.3.6.

We have JavaScript issues in the console and with this the whole website gets affected, partially crashing:

simple-lightbox.js?ver=3.3.6:1192
Uncaught TypeError: element.addEventListener is not a function
    at SimpleLightbox.addEventListener (simple-lightbox.js?ver=3.3.6:1192)
    at new SimpleLightbox (simple-lightbox.js?ver=3.3.6:187)
    at a.fn.init.$.fn.simpleLightbox (simple-lightbox.js?ver=3.3.6:1562)
    at nextgen_simplelightbox_init (nextgen_simple_lightbox_init.js?ver=3.3.6:14)
    at HTMLDocument.<anonymous> (nextgen_simple_lightbox_init.js?ver=3.3.6:17)
    at i (jquery.js?ver=1.12.4-wp:2)
    at Object.fireWith [as resolveWith] (jquery.js?ver=1.12.4-wp:2)
    at Function.ready (jquery.js?ver=1.12.4-wp:2)
    at HTMLDocument.J (jquery.js?ver=1.12.4-wp:2)

(index):1 Unchecked runtime.lastError: The message port closed before a response was received.

We tested the following:

– Rollback to NGG 3.3.5 fixed the problem. No more Javascript errors, and all is running smoothly again.
– We changed the lightbox used by NGG 3.3.6 from Simple Lightbox to Fancybox, and all is running smoothly again.
– Tested it on current browsers like Firefox or Chrome – problem occured everywhere.
– WordPress is 5.4.2, PHP is 7.4, MySQL is up-to-date, too
– We deactivated all plugins but the problem persisted.
– We changed the theme but the problem persisted.

Since in your last changelog you write something about changes in Simple Lightbox and all seems to point in that direction, we guess that there must be a problem somewhere.

Could you fix this – what can we do now?

Many greetings and thanks for your great plugin and help in advance,
-doffine