fix(audioconv): Ensure error logging works on quiet enabled

- Refactored `writeErrorLog` to return a promise, improving error handling when writing to the log file.
- Updated the error handling within `convertAudio` to ensure that error logs are written even when the `quiet` option is enabled (set to `true`).
- Refined log and console error outputs to make them conditional on the `quiet` option, improving clarity and control over error reporting.
- Added better handling for the log stream, including resolving on `finish` and rejecting on `error` to ensure reliability in the logging process.

lib/audioconv.js

@@ -242,23 +242,29 @@ async function checkFfmpeg(verbose=false) {
   return false;
 }
 
-function writeErrorLog(logFile, data, error) {
-  // Throw the error if the log file name is invalid
-  if (isNullOrUndefined(logFile) || typeof logFile !== 'string') {
-    throw error;
-  }
+async function writeErrorLog(logFile, data, error) {
+  // Return immediately if given log file is not a string type
+  if (isNullOrUndefined(logFile) || typeof logFile !== 'string') return;
 
   logFile = path.join(LOGDIR, path.basename(logFile));
   createDirIfNotExistSync(LOGDIR);
 
-  const logStream = fs.createWriteStream(logFile);
+  return new Promise((resolve, reject) => {
+    const logStream = fs.createWriteStream(logFile, { flags: 'a+', flush: true });
+
+    logStream.write(`[ERROR]<ACONV> ${error?.message || 'Unknown error'}${EOL}`);
+    logStream.write(`   Input Audio: ${data?.inputAudio || 'Unknown'}${EOL}`);
+    logStream.write(`   Output Audio: ${data?.outputAudio || 'Unknown'}${EOL}`);
+    logStream.write(`   File Size: ${data?.inputSize / (1024 * 1024) || '0.0'} MiB${EOL}`);
+    logStream.write(`---------------------------------------------${EOL}`);
+    logStream.end(EOL);
 
-  logStream.write(`[ERROR]<ACONV> ${error?.message || 'Unknown error'}${EOL}`);
-  logStream.write(`   Input Audio: ${data?.inputAudio || 'Unknown'}${EOL}`);
-  logStream.write(`   Output Audio: ${data?.outputAudio || 'Unknown'}${EOL}`);
-  logStream.write(`   File Size: ${data?.inputSize / (1024 * 1024) || '0.0'} MiB${EOL}`);
-  logStream.write(`---------------------------------------------${EOL}`);
-  logStream.end(EOL);
+    logStream.on('finish', () => resolve());
+    logStream.on('error', (err) => {
+      if (!logStream.destroyed) logStream.destroy();
+      reject(err);
+    });
+  });
 }
 
 
@@ -403,17 +409,18 @@ async function convertAudio(inFile, options = defaultOptions) {
     // Handlers
     ffmpegChain
       .on('error', (err) => {
-        if (!quiet) {
-          process.stdout.write('\n');
-          writeErrorLog(createLogFile('audioConvError'), {
-            inputFile: inFile,
-            outputFile: outFile,
-            inputSize: fs.statSync(inFile).size
-          }, err);
-          log.error('Failed to convert the audio file');
-          console.error('Caused by:', err.message);
-        }
-        reject(err);
+        quiet || process.stdout.write('\n');
+        writeErrorLog(createLogFile('audioConvError'), {
+          inputFile: inFile,
+          outputFile: outFile,
+          inputSize: fs.statSync(inFile).size
+        }, err).then(() => {
+          if (!quiet) {
+            log.error('Failed to convert the audio file');
+            console.error('Caused by:', err.message);
+          }
+          reject(err);
+        }).catch((errLog) => reject(new Error(errLog.message, { cause: err })));
       })
       .on('progress', (info) => {
         // Write the progress information to the console