title: Firebase import json adds all but then deletes everything
body: <p>I'm trying to use the import json feature on Firebase. Specifically, I have a collection of data looking like:</p>
  
  <pre><code>{
      "1":"hello",
      "2":"world",
      "more":"nothingSoFar",
  }
  </code></pre>
  
  <p>I want to overwrite the "more" section. So I click on "more", then hit "import json", and select my json file and click import. I see it adding all the nodes from my json file, but then the value of "more" switches to "null" and all the nodes get deleted from bottom to top like a collapsing accordion. </p>
  
  <p>What's going on here? Is my json file too large?</p>