phpstan level 7 for indexController.php (#5384)

Co-authored-by: Luc <sanchezluc+freshrss@gmail.com>

tests/phpstan-next.txt

@@ -3,7 +3,6 @@
 # Can be regenerated with something like:
 # find . -type d -name 'vendor' -prune -o -name '*.php' -exec sh -c 'vendor/bin/phpstan analyse --level 7 --memory-limit 512M {} >/dev/null 2>/dev/null || echo {}' \;
 
-./app/Controllers/indexController.php
 ./app/Controllers/userController.php
 ./app/Models/Feed.php
 ./app/Models/Share.php