onmozfullscreenchange warning in Firefox (not using react)

Question

I keep getting this error in Firefox console.

onmozfullscreenchange is deprecated. editresume.js:411:4
onmozfullscreenerror is deprecated. editresume.js:411:4
Ignoring get or set of property that has [LenientThis] because the “this” object is incorrect.

If I go to my code file, for that line number, this is what I have

tempbutton.setAttributeNode(attid);

and, I am not using onmozfullscreenchange or onmozfullscreenerror anywhere.

Why am I getting this? It is also triggers a debugger exception for some reason, at that line number.

Note : I dont get a similar error/warning/breakpoint trigger on Chrome. So, its Firefox only.

Firefox version - 70.0 Chrome version - 77.0.X

Answer 1

This message may appear when logging the window or document objects and extending the resulting message in the Console.

It's because these getters are configured to warn about this deprecation so that developers can update their code accordingly.
However, this deprecation notice doesn't look at what tried to get it, so when the Console itself tries to get the value of these properties, it will also trigger the warning notification.

But your debugger exception certainly comes from somewhere else.