message: fix pyramid loading logic
diff: @@ -65,15 +65,11 @@ export class DeepZoomPyramid {
  triggerLoad(id: DeepZoomTileID) {
  const record = this.currentTiles[id.toString()]
  - if (record) {
  - if (record.loaded) {
  - this.triggerLoad(DeepZoomTileID.create(id.level - 1, Math.floor(id.row / 2), Math.floor(id.col / 2)))
  - } else if (record.onShouldLoad) {
  + if (record && record.onShouldLoad) {
  record.onShouldLoad()
  record.onShouldLoad = null
  }
  }
  - }
  private _update() {
  // 25 is safe because that's like 2^25 pixels wide or tall.
  