Attach (recommended) or Link to PDF file here:
PDF from #4106, https://mail.gnome.org/archives/evince-list/2013-November/pdfNC0hkVW67a.pdf.

Steps to reproduce the problem:
1. Open the PDF

What is the expected behavior?
![immagine](https://user-images.githubusercontent.com/1616846/121865567-67ca4200-ccfe-11eb-8673-1d6e863fc8d5.png)

What went wrong?
The PDF doesn't load, `TypeError: can't access property Symbol(), match is null` error is logged in the console.
startColor = startColor ? startColor[$toStyle]() : "#FFFFFF";
    const endColor = this.color ? this.color[$toStyle]() : "#000000";
    const width = 5;
    const cmd = "repeating-linear-gradient";
    const colors = `${startColor},${startColor} ${width}px,${endColor} ${width}px,${endColor} ${
      2 * width
    }px`;
    switch (this.type) {
      case "crossHatch":
        return `${cmd}(to top,${colors}) ${cmd}(to right,${colors})`;
      case "crossDiagonal":
        return `${cmd}(45deg,${colors}) ${cmd}(-45deg,${colors})`;
      case "diagonalLeft":
        return `${cmd}(45deg,${colors})`;
      case "diagonalRight":
        return `${cmd}(-45deg,${colors})`;
      case "horizontal":
        return `${cmd}(to top,${colors})`;
      case "vertical":
        return `${cmd}(to right,${colors})`;
    }
    return "";
  }
}
class Picture extends StringObject {