BUG: Exception when "<v:page.rootline>" is used and pageUid doesn't exist

[Oktopuce]

I have checked that the bug exists in the dev-development branch
Yes.

I have checked that there are no already open issues or recently closed issues about this bug
Yes.

Describe the bug
When you're trying to get the root line of a page that doesn't exist, a PageNotFoundException exception is thrown:

(1/1) #1343589451 TYPO3\CMS\Core\Exception\Page\PageNotFoundException

To Reproduce
Steps to reproduce the behavior:

1. Insert in a Fluid Template, a bloc like this:

<v:page.rootline pageUid="{linkNotInDb}" as="theRootLine">
    ...
</v:page.rootline>

with {linkNotInDb} having a page Uid that doesn't exist in DB.

2. Display the page with this code in frontend
3. See exception

Expected behavior
No PageNotFoundException exception should be thrown

Additional context
In file vhs/Classes/Service/PageService.php, method getRootLine() the call to $rootLineUtility->get() must be surrounded by try{} catch()

try {
    /** @var RootlineUtility $rootLineUtility */
    $rootLineUtility = GeneralUtility::makeInstance(RootlineUtility::class, $pageUid);
    $rootline = $rootLineUtility->get();
} catch (PageNotFoundException $e) {
    return [];
}

[NamelessCoder]

I would argue that in this case it's desirable to get an exception and undesirable to suppress all warning/error output when a non-existing page is passed. Otherwise you're just left clueless about why you get an empty root line.

I suggest using v:try around the root line extracting ViewHelper - this also lets you render an alternative when this exception is raised.

[NamelessCoder]

I made the decision to reject this - it's undesirable to have this API suppress warnings about unreadable pages. See #1906 (comment).