Attach (recommended) or Link to PDF file here:  [test.pdf](https://akmer.aikucun.com/a94a8fe5ccb19ba61c4c0873d391e987982fbbd3_1616477914120_83.pdf)


Configuration:
- Web browser and its version: chrome 87.0.4280.88
- Operating system and its version: windows10
- PDF.js version: 2.6.347
- Is a browser extension:

Steps to reproduce the problem:
1. just open 

What is the expected behavior? (add screenshot)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/17724610/112087066-473f8f80-8bc8-11eb-8efb-56139ec42a9c.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

break;
          case "NumCopies":
            if (value > 0) {
              prefValue = value;
            }
            break;
          default:
            if (typeof value !== "boolean") {
              throw new FormatError(
                `viewerPreferences - expected a boolean value for: ${key}`
              );
            }
            prefValue = value;
        }
        if (prefValue !== undefined) {
          if (!prefs) {
            prefs = Object.create(null);
          }
          prefs[key] = prefValue;
        } else {
          info(`Bad value in ViewerPreferences for "${key}".`);
        }
      }
    }
    return shadow(this, "viewerPreferences", prefs);
  }
  /**
   * NOTE: "JavaScript" actions are, for now, handled by `get javaScript` below.
   */
  get openAction() {