[Bug] Blank page when resize happen during loading

[vince4]

I found an edge case pretty hard to reproduce.
When window.resize event is triggered while book.renderTo( is ongoing, the reader display a blank page with an empty div :

<div id="epubjs-container-42de2df8-43b2-4cb9-87b1-f371895d16de" class="epub-container" dir="ltr" style="word-spacing: 0px; line-height: 0; vertical-align: top; position: relative; display: flex; flex-flow: row; overflow: hidden; direction: ltr;"></div>

After long hours of exploration, I found that resize event empty the list of views in the manager.
Then, onResized get called in Rendition and should call display but it doesn't, because the location is not set already :

/**
   * Report resize events and display the last seen location
   * @private
   */
  onResized(size, epubcfi) {
    /**
     * Emit that the rendition has been resized
     * @event resized
     * @param {number} width
     * @param {height} height
     * @param {string} epubcfi (optional)
     * @memberof Rendition
     */
    this.emit(
      EVENTS.RENDITION.RESIZED,
      {
        width: size.width,
        height: size.height
      },
      epubcfi
    )

    if (this.location && this.location.start) {
      this.display(epubcfi || this.location.start.cfi)
    }
  }

I met two use cases. In the first one, the promise display was pending and in the second one, the promise display was completed.
I will try to propose a pull request soon.