Handling templates without a module name specified

Question

I have a 3rd party extension installed and I needed to overwrite on block because I could not use events or plugins on it.
The block is added in the layout file like this:

<block class="Vendor\Module\Block" name="some-name" template="path/to/template.phtml" />

Notice that there is no module name specified for the template.

I've overwritten it with this in my di.xml

<preference for="Vendor\Module\Block" type="MyVendor\MyModule\Block" />

now when loading a certain page I get the error path/to/template.phtml does not exist.

I know I can solve this by redeclaring the block in my own layout file and making the template Vendor_Module::path/to/module.phtml and it will work but this is not upgrade proof.
If I upgrade the extension and the template to that specific block changes I will have problems.

My question: Is there an upgrade proof way to overwrite blocks and still keep the templates from the original module?

Answer 1

Based on the comments, I was able solve my problem by adding this method to my block

public function getTemplate()
{
    $template = parent::getTemplate();
    $parts = \Magento\Framework\View\Asset\Repository::extractModule($template);
    if (empty($parts[0])) {
        $template = 'Vendor_Module'.\Magento\Framework\View\Asset\Repository::FILE_ID_SEPARATOR.$template;
    }
    return $template;
}

This way, if the template has a a module specified it will use that template, if not tell magento to load it from the original vendor module.