loadBackgroundObjects (shots) {
    shots
      .filter(shot => (shot.dialogNodes || []).length > 0)
      .forEach(({ dialogNodes }) =>
        dialogNodes
          .map(dialogNode => getBackgroundObject(dialogNode))
          .filter(bgObject => bgObject)
          .map(({ type: { slug } }) => slug)
          .filter(slug => slug)
          .forEach(slug => this.queueThangType(slug))
      )
  }
Queues up the background objects
@param {Shot[]} shots