Unable to use 'loudnorm' filter in fluent-ffmpeg

Version information

fluent-ffmpeg version: 2.1.2
ffmpeg version:
OS: built-in

Code to reproduce

I am new to node and i have use case where i need to validate the loudness parameters of an audio file and check if it is present in a given range and for this I want to measure the loudness parameters of the audio file using the loudnorm filter of ffmpeg and usage of 'loudnorm' filter in fluent-ffmpeg is throwing an error as mentioned below

const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path;
const Ffmpeg = require('fluent-ffmpeg');
Ffmpeg.setFfmpegPath(ffmpegPath);
const path = require('path');
var os = require('os');

const STREAM_URL = "any audio link";
const VOLUME_THRESHOLD = -50; // volume threshold
 let tmpfile = path.join(os.tmpdir(), 'name' + '.wav');

getLoudNormData(STREAM_URL, function(meanVolume){
  if(meanVolume <= VOLUME_THRESHOLD){
    console.log("WE HAVE A PROBLEM! VOLUME IS TOO LOW!");
  }else{
    console.log("ALL GOOD!");
  }
});

function getLoudNormData(streamUrl, callback){
console.log("inside");
 new Ffmpeg({ source: streamUrl })
  .withAudioFilter('loudnorm=I=-14:tp=-2:print_format=json')
  .addOption('-f', 'null')
  .on('start', function(ffmpegCommand){
    console.log('Output the ffmpeg command', ffmpegCommand);
  })
  .on('end', function(stdout, stderr){
    console.log('output is', stderr )
   // find the mean_volume in the output
    let meanVolumeRegex = stderr.match(/mean_volume:\s(-?[0–9]\d*(\.\d+)?)/);

    // return the mean volume
    if(meanVolumeRegex){
      let meanVolume = parseFloat(meanVolumeRegex[1]);
      console.log('mean volume is', meanVolume )
      return callback(meanVolume);
    }

    // if the stream is not available
    if(stderr.match(/Server returned 404 Not Found/)){
      return callback(false);
    }
 })
.save('-');
}

(note: if the problem only happens with some inputs, include a link to such an input file)

Expected results

{ "input_i" : "-27.61", "input_tp" : "-4.47", "input_lra" : "18.06", "input_thresh" : "-39.20", "output_i" : "-16.58", "output_tp" : "-1.50", "output_lra" : "14.78", "output_thresh" : "-27.71", "normalization_type" : "dynamic", "target_offset" : "0.58" }

above json in output of ffmpeg command

Observed results

Error: ffmpeg exited with code 1: Error opening filters! at ChildProcess.anonymous in fluent-ffmpeg/lib/processor.js — line 182

at ChildProcess.emit in core node:events — line 327

Checklist

[x] I have read the FAQ
[Y ] I tried the same with command line ffmpeg and it works correctly (hint: if the problem also happens this way, this is an ffmpeg problem and you're not reporting it to the right place)
[x] I have included full stderr/stdout output from ffmpeg

fluent-ffmpeg / node-fluent-ffmpeg