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.

f (!prperte.cte && prperte.haEncdng) {
        prperte.fallbackTUncde = th._leFntTUncde(prperte);
      }
      return prperte.tUncde;
    }
    
    
    
    
    
    f (!prperte.cte ) {
      return new TUncdeMap(th._leFntTUncde(prperte));
    }
    
    
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     A
    f (
      prperte.cte &&
      ((prperte.cMap.bultInCMap &&
        !(prperte.cMap ntancef IdenttyCMap)) ||
        (prperte.cdSytemInf.regtry === "Adbe" &&
          (prperte.cdSytemInf.rderng === "GB1" ||
            prperte.cdSytemInf.rderng === "CNS1" ||
            prperte.cdSytemInf.rderng === "Japan1" ||
            prperte.cdSytemInf.rderng === "Krea1")))
    ) {
       T
       a
       t