magento2,multistore,multidomain – Fixing Undefined Index: Store in Magento 2 Multi-Store and Multi-Domain

I am trying to set up my local mac to have 2 stores in 1 magento instance

The main domain (www.mydomain.dev) is working as expected however the french domain (www.mydomain-fr.dev) is not loading and giving me

1 exception(s):
Exception #0 (Exception): Notice: Undefined index: store; in /Users/myuser/Sites/mydomain/vendor/magento/module-store/Model/StoreResolver/ReaderList.php on line 50

Please could anyone advise? My vhost.conf looks like the following if it helps

  <VirtualHost *:443>
            ServerName mydomain.dev
            ServerAlias *.mydomain.dev
            Include "/Users/myuser/Sites/ssl/ssl-shared-cert.inc"
            CustomLog "/Users/myuser/Sites/logs/dev-access_log" combinedmassvhost
            ErrorLog "/Users/myuser/Sites/logs/dev-error_log"

            VirtualDocumentRoot /Users/myuser/Sites/mydomain
        </VirtualHost>

     <VirtualHost *:443>
            ServerName mydomain-fr.dev
            ServerAlias *.mydomain-fr.dev
            Include "/Users/myuser/Sites/ssl/ssl-shared-cert.inc"
            SetEnv MAGE_RUN_CODE frenchstore_view;
            SetEnv MAGE_RUN_TYPE store;
            CustomLog "/Users/myuser/Sites/logs/dev-access_log" combinedmassvhost
            ErrorLog "/Users/myuser/Sites/logs/dev-error_log"

            VirtualDocumentRoot /Users/myuser/Sites/mydomain
        </VirtualHost>

EDIT

If I update the index.php in root from:

$bootstrap = \Magento\Framework\App\Bootstrap::create(BP, $_SERVER);

To

$params = $_SERVER;
$params[\Magento\Store\Model\StoreManager::PARAM_RUN_CODE] = 'default'; 
$params[\Magento\Store\Model\StoreManager::PARAM_RUN_TYPE] = 'store';
$bootstrap = \Magento\Framework\App\Bootstrap::create(BP, $params);

Then the french domain works. Am I meant to be editing the index.php?

The store hierarchy is the following

Main website     UK Store        UK Store View
Main website     French Store    French Store View