Zend certified PHP/Magento developer

warning generated/code/Magento/Framework/App/Config/InitialConfigSource/Proxy.php

This is killing me.

When I run bin/magento setup:upgrade it throws this:

Warning:
include(/vendor/composer/../../generated/code/Magento/Framework/App/Config/InitialConfigSource/Proxy.php):
failed to open stream: No such file or directory in
/vendor/composer/ClassLoader.php on line 444

And when I run bin/magento setup:di:compile it throws this:

Class MagentoFrameworkAppResourceConnectionProxy does not exist

Site was running perfectly. I had run setup:upgrade before without any problem. I had also ran di:compile.

But today, all of sudden this is happening.

Any idea?