Cannot read property 'nativeElement' of undefined

[adrian-lg]

Issue type

I'm submitting a ... (check one with "x")

• bug report
• feature request

Issue description

Current behavior:

Console error in NbLayoutModule, on every page.

Expected behavior:

No errors.

Steps to reproduce:
Hard to tell, we don't use any html references to nativeElements in the code.

Other information:

npm, node, OS, Browser

<!--
Nebular: v4.1.2
Angular:9.0.4

The upgrade to the latest nebular didn't help.
-->

Angular, Nebular

<!--
TypeError: Cannot read property 'nativeElement' of undefined
    at NbLayoutComponent.getScrollPosition (index.js:7703)
    at NbLayoutComponent.scroll (index.js:7724)
    at SafeSubscriber._next (index.js:7576)
    at SafeSubscriber.__tryOrUnsub (Subscriber.js:183)
    at SafeSubscriber.next (Subscriber.js:122)
    at Subscriber._next (Subscriber.js:72)
    at Subscriber.next (Subscriber.js:49)
    at TakeWhileSubscriber.nextOrComplete (takeWhile.js:36)
    at TakeWhileSubscriber._next (takeWhile.js:31)
    at TakeWhileSubscriber.next (Subscriber.js:49)
-->

[andreipadolin]

Hi @adrian-lg please make sure that you are uses nb-layout.
Potentially it can be root cause

    <nb-layout>
        ... content here
    </nb-layout>

https://akveo.github.io/nebular/docs/components/layout/overview#nblayoutcomponent