When uploading a pdf file, I get Warning: Unimplemented widget field type "null", falling back to base field type at pdf.worker.js. The file is not loading.
I'm using the chrome browser. All other files are processed fine, but this one is not. Help solve the problem.
[usn2020.pdf](https://github.com/mozilla/pdf.js/files/5936611/usn2020.pdf)

) {
    const lines = text.split(/\r\n|\r|\n/);
    const buf = [];
    const totalWidth = width - 2 * hPadding;
    for (const line of lines) {
      const chunks = this._splitLine(line, font, fontSize, totalWidth);
      for (const chunk of chunks) {
        const padding = buf.length === 0 ? hPadding : 0;
        buf.push(
          this._renderText(
            chunk,
            font,
            fontSize,
            width,
            alignment,
            padding,
            -fontSize 
          )
        );
      }
    }
    const renderedText = buf.join("\n");
    return (
      "/Tx BMC q BT " +
      defaultAppearance +
      ` 1 0 0 1 0 ${height} Tm ${renderedText}` +
      " ET Q EMC"
    );
  }
  _splitLine(line, font, fontSize, width) {