Errors when installing module

Problem/Motivation

This is a two part problem.

Unable to install module due to error:

  You have requested a non-existent service "Drupal\state_machine_ui\Hook\Sta  
  teMachineUiHooks".  

Fixed by verifying the install hook only fires in the runtime phase, otherwise the service is not yet loaded from the module.

After the module is installed, this error appears on cache clear:

Error: Class "Symfony\Component\Config\Loader\FileLoader" not found in /var/www/html/vendor/symfony/dependency-injection/Loader/FileLoader.php on line 37 #0 /var/www/html/vendor/composer/ClassLoader.php(576): include()
#1 /var/www/html/vendor/composer/ClassLoader.php(427): {closure:Composer\Autoload\ClassLoader::initializeIncludeClosure():575}()
#2 /var/www/html/vendor/symfony/dependency-injection/Loader/YamlFileLoader.php(41): Composer\Autoload\ClassLoader->loadClass()

The FileLoader class is provided by symfony/config, which is a dev dependency of symfony/dependency-injection.

I'll try adding it to this module's composer.json. I'm not sure if that's the right fix, but after adding it to my project's composer.json, cache clear is working.

Test by adding this to your root composer.json, above packages.drupal.org:

    "repositories": [
        {
            "type": "vcs",
            "url": "git@git.drupal.org:issue/state_machine_ui-3608746.git"
        },
    ]

Then require it with:
composer require drupal/state_machine_ui:dev-3608746-fix_error -W