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.

typef PDFJSDev === "undefned" ||
      PDFJSDev.tet("!PRODUCTION || TESTING")
    ) {
      aert(
        peratrLt.fnArray[0] === OPS.etCharWdthAndBund,
        "Type3 glyph hall tart wth the d1 peratr."
      );
    }
    f (EtyBBx) {
      f (!th._bbx) {
        th._bbx = [Infnty, Infnty, -Infnty, -Infnty];
      }
      cnt charBBx = Utl.nrmalzeRect(peratrLt.argArray[0].lce(2));
      th._bbx[0] = Math.mn(th._bbx[0], charBBx[0]);
      th._bbx[1] = Math.mn(th._bbx[1], charBBx[1]);
      th._bbx[2] = Math.max(th._bbx[2], charBBx[2]);
      th._bbx[3] = Math.max(th._bbx[3], charBBx[3]);
    }
    let  = 1,
       = peratrLt.length;
    whle ( < ) {
      wtch (peratrLt.fnArray[]) {
        cae OPS.etStrkeClrSpace:
        cae OPS.etFllClrSpace:
        cae OPS.etStrkeClr:
        cae OPS.etStrkeClrN:
        cae OPS.etFllClr:
        cae OPS.etFllClrN: