Attach (recommended) or Link to PDF file here:
[PATTYP2.pdf](https://github.com/mozilla/pdf.js/files/6471935/PATTYP2.pdf)

Configuration:
- Web browser and its version: FF 88.0.1
- Operating system and its version: W10.0.19042.985
- PDF.js version: https://mozilla.github.io/pdf.js/web/viewer.html

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

What is the expected behavior? (add screenshot)
![grafik](https://user-images.githubusercontent.com/6665575/118114800-5e407800-b3e8-11eb-860f-019f48a8eabf.png)

What went wrong? (add screenshot)
![grafik](https://user-images.githubusercontent.com/6665575/118114841-6c8e9400-b3e8-11eb-8252-1517e5d76475.png)

(memo for me: when fixed, check the files in https://issues.apache.org/jira/browse/PDFBOX-1958 )

unreachable("Should not call beginImageData");
    }
    paintFormXObjectBegin(matrix, bbox) {
      if (!this.contentVisible) {
        return;
      }
      this.save();
      this.baseTransformStack.push(this.baseTransform);
      if (Array.isArray(matrix) && matrix.length === 6) {
        this.transform.apply(this, matrix);
      }
      this.baseTransform = this.ctx.mozCurrentTransform;
      if (bbox) {
        const width = bbox[2] - bbox[0];
        const height = bbox[3] - bbox[1];
        this.ctx.rect(bbox[0], bbox[1], width, height);
        this.clip();
        this.endPath();
      }
    }
    paintFormXObjectEnd() {
      if (!this.contentVisible) {
        return;
      }
      this.restore();
      this.baseTransform = this.baseTransformStack.pop();
    }
    beginGroup(group) {