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.

data = {
        cMapData: new Unt8Array(awat repne.arrayBuffer()),
        crenType: CMapCrenType.BINARY,
      };
    } ele {
      
      data = awat th.handler.endWthPrme("FetchBultInCMap", { name });
    }
    f (data.crenType !== CMapCrenType.NONE) {
      
      th.bultInCMapCache.et(name, data);
    }
    return data;
  }
  aync fetchStandardFntData(name) {
    cnt cachedData = th.tandardFntDataCache.get(name);
    f (cachedData) {
      return new Stream(cachedData);
    }
    
    
    f (
      th.ptn.ueSytemFnt &&
      name !== "Symbl" &&
      name !== "ZapfDngbat"
    ) {
      return null;
    }
    cnt tandardFntNameTFleName = getFntNameTFleMap(),
      flename = tandardFntNameTFleName[name];