2.2.9 causes fatal error

Updating to 2.2.9 crashed my site. After deleting the plugin and attempting to reinstall, I get this error:

Plugin could not be activated because it triggered a fatal error.

Warning: require(…/wp-content/plugins/postmatic/vendor/composer/../symfony/polyfill-ctype/bootstrap.php): failed to open stream: No such file or directory in …/wp-content/plugins/postmatic/vendor/composer/autoload_real.php on line 70