How to see if data store exists

I need to see if it exist in a flow. I have tried every trick I can think of:

{
  condition: {
    if: "{{localStorage.getItem('datastore_datastoreusers') != null}}", // if: "{{datastoreusers}}", // if: "{{datastoreusers.data}}",
    then: {
      steps: {
        runJS: {
          function: "eval",
          args: ["console.log('No Pre run')"]
        }
      }
    },
    else: {
      steps: [
        {
          runJS: {
            function: "eval",
            args: ["console.log('Pre run')"]
          }
        },
        {
          run: {action: "{{app.f7view.users.getusers.load()}}"}
        }
      ]
    }
  }
}

and: