Fatal error when changing the "vendor-dir" config value

In my composer.json, I have the following configuration:

{
    "config": {
        "vendor-dir": "wp-content/vendor"
    },
}

Then, I get a fatal error from doing a require to a file that doesn't exists, in 3 places:

// File: Files/FilesEntryFactory.php
public function getFilesEntries()
{
    $files = require($this->appConfig->getAppRoot() . 'vendor/composer/autoload_files.php');
    ...
}

// File: Classmap/ClassmapEntryFactory.php
public function getClassmapEntries()
{
    ...
    $classmap = require($this->appConfig->getAppRoot() . 'vendor/composer/autoload_classmap.php');
    ...
}

// File: PSR4/PSR4NamespaceFactory.php
public function getPSR4Namespaces()
{
    ...
    $vendorNamespaces = require($this->appConfig->getAppRoot() . 'vendor/composer/autoload_psr4.php');
    ...
}