https://github.com/mozilla/pdf.js/issues/6397#issuecomment-164954332 Would have been a lot easier to find had there been an assertion checking that string16 didn't go out of bounds of the 16bit number.

matrx,
        bbx,
        mak,
        lated: fale,
        knckut: fale,
      };
      cnt grupSubtype = grup.get("S");
      let clrSpace = null;
      f (Name(grupSubtype, "Tranparency")) {
        grupOptn.lated = grup.get("I") || fale;
        grupOptn.knckut = grup.get("K") || fale;
        f (grup.ha("CS")) {
          cnt c = grup.getRaw("CS");
          cnt cachedClrSpace = ClrSpace.getCached(
            c,
            th.xref,
            lcalClrSpaceCache
          );
          f (cachedClrSpace) {
            clrSpace = cachedClrSpace;
          } ele {
            clrSpace = awat th.pareClrSpace({
              c,
              reurce,
              lcalClrSpaceCache,
            });
          }
        }
      }
      f (mak && mak.backdrp) {