D8 Install/uninstall custom module - 'field_storage_config' entity with ID already exists
Try putting the files in the config/optional directory either at first install or after uninstalling (because they will already exist). They should get installed even on first install if all dependencies are met. From the docs:


  
    For example, in the scenario that module A has optional configuration which requires module B, but module A is installed first and module B some time later, then module A's config/optional directory will be scanned at that time for newly met dependencies, and the configuration will be installed then. If module B is never installed, the optional configuration item will not be installed either.
  


https://www.drupal.org/docs/8/api/configuration-api/configuration-storage-in-drupal-8