
Attach (recommended) or Link to PDF file here:
[NAPEN16171380959.pdf](https://github.com/mozilla/pdf.js/files/6143802/NAPEN16171380959.pdf)

Configuration:
- Web browser and its version: Firefox 88 Nightly
- Operating system and its version: Windows 10
- PDF.js version:
- Is a browser extension: No

What went wrong? (add screenshot)
![](https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-03-15-10-58-27-ce2796.png)


for (j = 0; j < n; j++) {
                stack.push(data[i++]);
              }
            }
          } else if ((op & 0xf8) === 0xb8) {
            
            n = op - 0xb8 + 1;
            if (inFDEF || inELSE) {
              i += n * 2;
            } else {
              for (j = 0; j < n; j++) {
                b = data[i++];
                stack.push((b << 8) | data[i++]);
              }
            }
          } else if (op === 0x2b && !tooComplexToFollowFunctions) {
            
            if (!inFDEF && !inELSE) {
              
              funcId = stack[stack.length - 1];
              if (isNaN(funcId)) {
                info("TT: CALL empty stack (or invalid entry).");
              } else {
                ttContext.functionsUsed[funcId] = true;
                if (funcId in ttContext.functionsStackDeltas) {
                  const newStackLength =
                    stack.length + ttContext.functionsStackDeltas[funcId];
                  if (newStackLength < 0) {
                    warn("TT: CALL invalid functions stack delta.");
                    ttContext.hintsValid = false;