How to use the thrift.Thrift.TApplicationExceptionType function in thrift

TBufferedTransport.receiver(function(transin) {
    var protin = new TBinaryProtocol(transin);
    var transout = new TBufferedTransport(undefined, function(buf) {
      callback.sendReply(buf);
    });
    var protout = new TBinaryProtocol(transout);
    try {
     processor.process(protin, protout);
    } catch (err) {
      console.log(err);
      var x = new Thrift.TApplicationException(
        Thrift.TApplicationExceptionType.UNKNOWN_METHOD,
        'Unknown error'
      );
      protout.writeMessageBegin('', Thrift.MessageType.Exception, 0);
      x.write(protout);
      protout.writeMessageEnd();
      protout.flush();
    }
  })(datain);
}

UserStoreProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

MetadataServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

FlowServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

MetricsFrontendServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

AuthorizationServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

MetricsFrontendServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

AppFabricServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}

private missingResult = (func: ThriftFile.IFunction) => {
    if (func.returnTypeId === "void") {
      return {data: null, exception: null};
    }
    return {
      data: new Thrift.TApplicationException(
        Thrift.TApplicationExceptionType.MISSING_RESULT,
        `Mimic: no data found for function '${func.name}'`,
      ),
      exception: "MISSING_RESULT",
    };
  }

FARServiceProcessor.prototype.process = function(input, output) {
  var r = input.readMessageBegin();
  if (this['process_' + r.fname]) {
    return this['process_' + r.fname].call(this, r.rseqid, input, output);
  } else {
    input.skip(Thrift.Type.STRUCT);
    input.readMessageEnd();
    var x = new Thrift.TApplicationException(Thrift.TApplicationExceptionType.UNKNOWN_METHOD, 'Unknown function ' + r.fname);
    output.writeMessageBegin(r.fname, Thrift.MessageType.Exception, r.rseqid);
    x.write(output);
    output.writeMessageEnd();
    output.flush();
  }
}