fix(audioconv): Improve ffmpeg bin check and error handling

- Removed the promisified `exec` call for `ffmpeg -version` check and replaced it with a more reliable `spawnSync` approach.
- Refined the environment variable check for `FFMPEG_PATH` to ensure it is not null or undefined before proceeding.
- Enhanced `splitOptions` to correctly handle options without values, avoiding accidental concatenation with subsequent options.
- Streamlined error handling and logging for better clarity during the `ffmpeg` check process.

lib/audioconv.js

@@ -31,7 +31,6 @@ const fs = require('fs');
 const path = require('path');
 const childProcess = require('node:child_process');
 const { EOL } = require('node:os');
-const { promisify } = require('node:util');
 const ffmpeg = require('fluent-ffmpeg');
 
 const {
@@ -43,10 +42,6 @@ const {
   isNullOrUndefined
 } = require('./utils');
 
-// Promisify the `exec` function
-const exec = promisify(childProcess.exec);
-
-
 /**
  * Options for configuring the audio conversion.
  *
@@ -129,7 +124,13 @@ function splitOptions(options) {
       if (option.startsWith('-')) {
         valueIndex = index + 1;
         if (valueIndex < optionsList.length) {
-          resolvedOptions.push(`${option} ${optionsList[valueIndex]}`);
+          // Check if the next argument is not an option that starts with hyphen
+          if (!optionsList[valueIndex].startsWith('-')) {
+            resolvedOptions.push(`${option} ${optionsList[valueIndex]}`);
+          // Otherwise, only push the option without the next argument as value
+          } else {
+            resolvedOptions.push(option);
+          }
         } else {
           resolvedOptions.push(option);
         }
@@ -216,7 +217,7 @@ function resolveOptions(options, useDefault=true) {
  */
 async function checkFfmpeg(verbose=false) {
   verbose && log.debug('Checking `ffmpeg` binary...');
-  if (process.env.FFMPEG_PATH || process.env.FFMPEG_PATH !== '') {
+  if (!isNullOrUndefined(process.env.FFMPEG_PATH) && process.env.FFMPEG_PATH !== '') {
     if ((await fs.promises.stat(process.env.FFMPEG_PATH)).isDirectory()) {
       const msg = '[EISDIR] Please set the FFMPEG_PATH environment variable '
         + 'to the path of the `ffmpeg` binary';
@@ -228,26 +229,17 @@ async function checkFfmpeg(verbose=false) {
     return true;
   }
 
-  // This try-catch block to handle error,
-  // in case the `ffmpeg` binary is not installed on system
-  try {
-    const { status } = await exec('ffmpeg -version');
-    if (status !== 0) {
-      verbose && log.debug('`ffmpeg` installed on system');
-      return true;
-    }
-
-    verbose && log.error('`ffmpeg` not installed on system');
-    return false;
-  /* eslint-disable-next-line no-unused-vars
-     ---
-     Only need to ensure that the `spawn` call is correctly executed
-     to check FFmpeg; if error occurred, that means the `ffmpeg` command
-     are not recognized */
-  } catch (_err) {
-    verbose && log.error('`ffmpeg` not installed on system');
-    return false;
+  const { status } = childProcess.spawnSync('ffmpeg', ['-version'], {
+    shell: true,       // For Windows, would cause error if this set to false
+    windowsHide: true
+  });
+  if (status === 0) {
+    verbose && log.debug('`ffmpeg` installed on system');
+    return true;
   }
+
+  verbose && log.error('`ffmpeg` not installed on system');
+  return false;
 }
 
 function writeErrorLog(logFile, data, error) {