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):

!Number.isInteger(offsetFieldWidth) ||
          !Number.isInteger(generationFieldWidth)
        ) {
          throw new FormatError(
            `Invalid XRef entry fields length: ${first}, ${n}`
          );
        }
        for (i = streamState.entryNum; i < n; ++i) {
          streamState.entryNum = i;
          streamState.streamPos = stream.pos;
          var type = 0,
            offset = 0,
            generation = 0;
          for (j = 0; j < typeFieldWidth; ++j) {
            type = (type << 8) | stream.getByte();
          }
          
          if (typeFieldWidth === 0) {
            type = 1;
          }
          for (j = 0; j < offsetFieldWidth; ++j) {
            offset = (offset << 8) | stream.getByte();
          }
          for (j = 0; j < generationFieldWidth; ++j) {
            generation = (generation << 8) | stream.getByte();
          }
          var entry = {};
          entry.offset = offset;
          entry.gen = generation;
          switch (type) {