fix azure cannot download mp3 if encodingMp3 = true

lib/routes/api/tts-cache.js

@@ -96,17 +96,27 @@ router.post('/Synthesize', async(req, res) => {
     let readStream = fs.createReadStream(filePath);
     if (['nuance', 'nvidia'].includes(cred.vendor) ||
       (
-        process.env.JAMBONES_TTS_TRIM_SILENCE &&
+        (process.env.JAMBONES_TTS_TRIM_SILENCE || !process.env.JAMBONES_DISABLE_TTS_STREAMING) &&
         ['microsoft', 'azure'].includes(cred.vendor)
       )
     ) {
       if (encodingMp3) {
-        readStream = readStream
+        readStream = pipeline(
-          .pipe(new PCMToMP3Encoder({
+          readStream,
+          new PCMToMP3Encoder({
             channels: 1,
             sampleRate: 8000,
             bitRate: 128
-          }, logger));
+          }, logger),
+          (err) => {
+            if (err) {
+              logger.error('ttscache/Synthesize failed:', err);
+              if (!res.headersSent) {
+                res.status(500).end('Server error');
+              }
+            }
+          }
+        );
       } else {
         contentType = 'application/octet-stream';
       }