STR:
  - Go to https://mozilla.github.io/pdf.js/web/viewer.html
  - Click on "Open File" and open a pdf

The `Download` button and the `Current view` one just disappear.
I can reproduce this bug with Firefox nightly, Chrome stable and Epiphany on debian.
if (!this.documentInfo) {
      
      
      await new Promise(resolve => {
        this.eventBus._on("metadataloaded", resolve, { once: true });
      });
      if (pdfDocument !== this.pdfDocument) {
        return null; 
      }
    }
    if (!this._contentLength) {
      
      
      
      
      
      await new Promise(resolve => {
        this.eventBus._on("documentloaded", resolve, { once: true });
      });
      if (pdfDocument !== this.pdfDocument) {
        return null; 
      }
    }
    return {