Error when package is not installed in vendor

[prudloff-insite]

The integrity command crashes when a package is not installed in vendor:

In Hasher.php line 19:
                                                                                                
  [ErrorException]                                                                              
  scandir(/var/www/vendor/algolia/places): Failed to open directory: No such file or directory  
                                                                                                

Exception trace:
  at /var/www/vendor/sansec/composer-integrity-plugin/src/Hasher.php:19
 Composer\Util\ErrorHandler::handle() at n/a:n/a
 scandir() at /var/www/vendor/sansec/composer-integrity-plugin/src/Hasher.php:19
 Sansec\Integrity\Hasher->getPackageFiles() at /var/www/vendor/sansec/composer-integrity-plugin/src/Hasher.php:42
 Sansec\Integrity\Hasher->generatePackageDataHash() at /var/www/vendor/sansec/composer-integrity-plugin/src/PackageSubmitter.php:35
 Sansec\Integrity\PackageSubmitter->getPackages() at /var/www/vendor/sansec/composer-integrity-plugin/src/PackageSubmitter.php:85
 Sansec\Integrity\PackageSubmitter->getPackageVerdicts() at /var/www/vendor/sansec/composer-integrity-plugin/src/IntegrityCommand.php:65
 Sansec\Integrity\IntegrityCommand->execute() at phar:///usr/local/bin/composer2/vendor/symfony/console/Command/Command.php:298
 Symfony\Component\Console\Command\Command->run() at phar:///usr/local/bin/composer2/vendor/symfony/console/Application.php:1040
 Symfony\Component\Console\Application->doRunCommand() at phar:///usr/local/bin/composer2/vendor/symfony/console/Application.php:301
 Symfony\Component\Console\Application->doRun() at phar:///usr/local/bin/composer2/src/Composer/Console/Application.php:382
 Composer\Console\Application->doRun() at phar:///usr/local/bin/composer2/vendor/symfony/console/Application.php:171
 Symfony\Component\Console\Application->run() at phar:///usr/local/bin/composer2/src/Composer/Console/Application.php:145
 Composer\Console\Application->run() at phar:///usr/local/bin/composer2/bin/composer:93
 require() at /usr/local/bin/composer2:29

It is possible to use https://github.com/composer/installers to install packages elsewhere.

I am testing with composer-integrity-plugin 0.2.1.