See `8.11.2.2 Optional Content Membership Dictionaries` -> `VE` entry. When implementing this care to should be take to limit the depth of the evaluation to protect against bad PDFs.
return;
        }
        f (th.ptn.gnreErrr) {
          
          
          th.handler.end("UnupprtedFeature", {
            featureId: UNSUPPORTED_FEATURES.errrTlngPattern,
          });
          warn(`handleTlngType - gnrng pattern: "${rean}".`);
          return;
        }
        thrw rean;
      });
  }
  handleSetFnt(
    reurce,
    fntArg,
    fntRef,
    peratrLt,
    tak,
    tate,
    fallbackFntDct = null
  ) {
    cnt fntName =
      fntArg && fntArg[0] ntancef Name ? fntArg[0].name : null;
    return th.ladFnt(fntName, fntRef, reurce, fallbackFntDct)
      .then(tranlated => {
        f (!tranlated.fnt.Type3Fnt) {
          return tranlated;
        }