composer install error I can't install anything because of this error:


  [RuntimeException]
    Could not scan for classes inside "/app/vendor/symfony/serializer/src/" which does not appear to be a file nor a folder


and subsequently:


  Could not scan for classes inside "/app/vendor/symfony/yaml/src/" which does not appear to be a file nor a folder


I navigated to that directory and the src folder is indeed missing...

I'm using Lando and switch the PHP to 7.1. I tried deleting the vendor directory and rerunning lando composer update and lando composer install but get the same errors.
Could be and over lap of composer requests. This example is for Pantheon resipe but it may help https://github.com/lando/lando/issues/340