Attach (recommended) or Link to PDF file here:
[PDFBOX-5275-p5.pdf](https://github.com/mozilla/pdf.js/files/7109095/PDFBOX-5275-p5.pdf)

Configuration:
- Web browser and its version: FF 91.0.2
- Operating system and its version: Windows 10.0.19043.1165
- PDF.js version: latest (tried with https://mozilla.github.io/pdf.js/web/viewer.html )

Steps to reproduce the problem:
1. open the file
2.

What is the expected behavior? Displays a plant

What went wrong? Displays blank page

See also
https://issues.apache.org/jira/browse/PDFBOX-5275
which had the same problem, the cause was bad handling of an empty OCGs entry

![grafik](https://user-images.githubusercontent.com/6665575/132079956-c48921bf-6dbb-4e89-886e-4301d955ee35.png)


return true;
      }
      switch (operator) {
        case "And":
          if (!state) {
            return false;
          }
          break;
        case "Or":
          if (state) {
            return true;
          }
          break;
        case "Not":
          return !state;
        default:
          return true;
      }
    }
    return operator === "And";
  }
  isVisible(group) {
    if (!group) {
      warn("Optional content group not defined.");
      return true;
    }
    if (group.type === "OCG") {
      if (!this._groups.has(group.id)) {
        warn(`Optional content group not found: ${group.id}`);
        return true;