If test failures or errors exist and screenshots are enabled, then screenshots are taken prior to sending the DELETE.

To enable screenshots for test failures/errors, set the screenshots property in your nightwatch.json, under the desired test_settings environment. E.g.:

nightwatch.json

{
  "test_settings" : {
    "default" : {
      "screenshots" : {
        "enabled" : true,
        "on_failure" : true,
        "path" : "./screens"
      }
    }
  }
}