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.
} else {
        
        
        ticks = PDFViewerApplication.accumulateWheelTicks(delta);
      }
    } else {
      
      const PIXELS_PER_LINE_SCALE = 30;
      ticks = PDFViewerApplication.accumulateWheelTicks(
        delta / PIXELS_PER_LINE_SCALE
      );
    }
    if (ticks < 0) {
      PDFViewerApplication.zoomOut(-ticks);
    } else if (ticks > 0) {
      PDFViewerApplication.zoomIn(ticks);
    }
    const currentScale = pdfViewer.currentScale;
    if (previousScale !== currentScale) {
      
      
      
      const scaleCorrectionFactor = currentScale / previousScale - 1;
      const rect = pdfViewer.container.getBoundingClientRect();
      const dx = evt.clientX - rect.left;
      const dy = evt.clientY - rect.top;
      pdfViewer.container.scrollLeft += dx * scaleCorrectionFactor;
      pdfViewer.container.scrollTop += dy * scaleCorrectionFactor;
    }
  } else {