[Bug Report] v-lazy doesn't work at all if transition prop is falsey

[Alex-Mastin]

Environment

Vuetify Version: 2.3.3
Vue Version: 2.6.11
Browsers: Google Chrome
OS: Windows

Steps to reproduce

If you just take an example for v-lazy from the Vuetify docs and change the transition prop to something falsey, such as '', you will find that lazy loading stops working altogether.

Expected Behavior

Lazy loading should still work if you provide a falsey value, and the elements inside of v-lazy shouldn't appear in the HTML until you scroll to them.

Actual Behavior

Lazy loading does not work without some truthy value in the transition prop. The threshold is completely ignored, and any elements inside of the v-lazy element are visible in the HTML before you have scrolled those elements into view.

Reproduction Link

https://codepen.io/HeadAdmiral/pen/eYJMpgG

Other comments

The change needs to occur in genContent() inside VLazy.ts. Just some different conditionality instead of returning the slot content if the transition prop is falsey.