VideoPress: VideoPress Video block outputs null

[retrofox]

The VideoPress Video block outputs null in the front end when the block doesn't have a defined video.

Block editor	Front-end

[dhasilva]

The null output happens here, when videoPressUrl is null: https://github.com/Automattic/jetpack/blob/trunk/projects/packages/videopress/src/client/block-editor/blocks/video/save.js#L67

<div className="jetpack-videopress-player__wrapper">
	{ `\n${ videoPressUrl }\n` /* URL needs to be on its own line. */ }
</div>

A simple check fixes this:

{ videoPressUrl && (
	<div className="jetpack-videopress-player__wrapper">
		{ `\n${ videoPressUrl }\n` /* URL needs to be on its own line. */ }
	</div>
) }

The problem is that this triggers the block's validation, as the save content is different from what was previously saved to the database:

The block user would need to manually update the offending block instances which, to be fair, I think should not be a problem as we are talking about a specific case that should not be common.

There is an issue about this, for reference: WordPress/gutenberg#7604