First install throw error `Route "backerymails.settings" does not exist.`

Problèmes/Motivations

When enabling for the first time Backerymails, it throw an error Route "backerymails.settings" does not exist.

Step to reproduce:

1. Install via Composer
2. Enable it using drush en backerymails -y
3. It will then throw the following error:

The following extensions will be enabled: backerymails
Do you really want to continue? (y/n): y
Symfony\Component\Routing\Exception\RouteNotFoundException: Route "backerymails.settings" does not exist. in                                     [error]
/Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Routing/RouteProvider.php:190
Stack trace:
#0 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Routing/UrlGenerator.php(419):
Drupal\Core\Routing\RouteProvider->getRouteByName('backerymails.se...')
#1 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Routing/UrlGenerator.php(269):
Drupal\Core\Routing\UrlGenerator->getRoute('backerymails.se...')
#2 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Render/MetadataBubblingUrlGenerator.php(105):
Drupal\Core\Routing\UrlGenerator->generateFromRoute('backerymails.se...', Array, Array, true)
#3 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Url.php(753):
Drupal\Core\Render\MetadataBubblingUrlGenerator->generateFromRoute('backerymails.se...', Array, Array, false)
#4 /Users/drupal_user/www/contrib/drupal/backerymails/backerymails.install(15): Drupal\Core\Url->toString()
#5 [internal function]: backerymails_install()
#6 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Extension/ModuleHandler.php(391):
call_user_func_array('backerymails_in...', Array)
#7 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/Extension/ModuleInstaller.php(291):
Drupal\Core\Extension\ModuleHandler->invoke('backerymails', 'install')
#8 /Users/drupal_user/www/contrib/drupal/_sandbox/web/core/lib/Drupal/Core/ProxyClass/Extension/ModuleInstaller.php(83):
Drupal\Core\Extension\ModuleInstaller->install(Array, true)
#9 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/commands/core/drupal/environment.inc(131):
Drupal\Core\ProxyClass\Extension\ModuleInstaller->install(Array, true)
#10 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/commands/core/drupal/environment.inc(198): drush_module_install(Array)
#11 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/commands/pm/pm.drush.inc(1180): drush_module_enable(Array)
#12 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/includes/command.inc(422): drush_pm_enable('backerymails')
#13 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/includes/command.inc(231): _drush_invoke_hooks(Array, Array)
#14 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/includes/command.inc(199): drush_command('backerymails')
#15 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/lib/Drush/Boot/BaseBoot.php(67): drush_dispatch(Array)
#16 /Users/drupal_user/www/contrib/drupal/_sandbox/vendor/drush/drush/includes/preflight.inc(66): Drush\Boot\BaseBoot->bootstrap_and_dispatch()
#17 phar:///Users/drupal_user/bin/drush9/drush.phar/bin/drush.php(159): drush_main()
#18 /Users/drupal_user/bin/drush9/drush.phar(10): require('phar:///Users/w...')
#19 {main}