Trying to read a pdf file using PDFJS.getDocument function. The pdf worker is throwing


UnknownErrorException {
 name: "UnknownErrorException", 
 message: "Invalid root reference", 
 details: "FormatError: Invalid root reference"
}

The error can be easily reproduced calling PDFJS.getDocument(pdfUrl) using the attached pdf
[110229_10312017_6810306.pdf](https://github.com/mozilla/pdf.js/files/1444166/110229_10312017_6810306.pdf)


this.readXRef( true);
    }
    
    let trailerDict, trailerError;
    for (const trailer of [...trailers, "generationFallback", ...trailers]) {
      if (trailer === "generationFallback") {
        if (!trailerError) {
          break; 
        }
        this._generationFallback = true;
        continue;
      }
      stream.pos = trailer;
      const parser = new Parser({
        lexer: new Lexer(stream),
        xref: this,
        allowStreams: true,
        recoveryMode: true,
      });
      const obj = parser.getObj();
      if (!isCmd(obj, "trailer")) {
        continue;
      }
      
      const dict = parser.getObj();
      if (!(dict instanceof Dict)) {
        continue;
      }
      
      try {