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)


!Number.isInteger(entry.gen) ||
          !(entry.free || entry.uncompressed)
        ) {
          throw new FormatError(
            `Invalid entry in XRef subsection: ${first}, ${count}`
          );
        }
        
        
        if (i === 0 && entry.free && first === 1) {
          first = 0;
        }
        if (!this.entries[i + first]) {
          this.entries[i + first] = entry;
        }
      }
      tableState.entryNum = 0;
      tableState.streamPos = stream.pos;
      tableState.parserBuf1 = parser.buf1;
      tableState.parserBuf2 = parser.buf2;
      delete tableState.firstEntryNum;
      delete tableState.entryCount;
    }
    
    if (this.entries[0] && !this.entries[0].free) {
      throw new FormatError("Invalid XRef table: unexpected first object");
    }
    return obj;
  }
  processXRefStream(stream) {