Attach (recommended) or Link to PDF file here:  [test.pdf](https://akmer.aikucun.com/a94a8fe5ccb19ba61c4c0873d391e987982fbbd3_1616477914120_83.pdf)


Configuration:
- Web browser and its version: chrome 87.0.4280.88
- Operating system and its version: windows10
- PDF.js version: 2.6.347
- Is a browser extension:

Steps to reproduce the problem:
1. just open 

What is the expected behavior? (add screenshot)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/17724610/112087066-473f8f80-8bc8-11eb-8efb-56139ec42a9c.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

(ch >=  0x61 && ch <=  0x66)
      ) {
        digit = (ch & 0x0f) + 9;
      } else if (ch ===  0x3e) {
        this.eof = true;
        break;
      } else {
        
        continue;
      }
      if (firstDigit < 0) {
        firstDigit = digit;
      } else {
        buffer[bufferLength++] = (firstDigit << 4) | digit;
        firstDigit = -1;
      }
    }
    if (firstDigit >= 0 && this.eof) {
      
      buffer[bufferLength++] = firstDigit << 4;
      firstDigit = -1;
    }
    this.firstDigit = firstDigit;
    this.bufferLength = bufferLength;
  };
  return AsciiHexStream;
})();
var RunLengthStream = (function RunLengthStreamClosure() {
  
  function RunLengthStream(str, maybeLength) {