fix(tts): handle empty audio from kokoro_onnx.create() gracefully

visualnovel/tts.py

@@ -169,11 +169,21 @@ class KokoroTTS:
                 fallback[seed % len(fallback)] if fallback else next(iter(self._available_voices))
             )
 
+        text = text.strip()
+        if not text:
+            return None
+
         cache_key = hashlib.sha256(f"{text}\x00{voice_id}\x00{seed}".encode()).hexdigest()
         if cache_key in self._cache:
             return self._cache[cache_key]
 
-        samples, sample_rate = self._kokoro.create(text, voice=voice_id, speed=1.0, lang="en-us")
+        try:
+            samples, sample_rate = self._kokoro.create(text, voice=voice_id, speed=1.0, lang="en-us")
+        except (ValueError, Exception):
+            return None
+
+        if samples is None or (hasattr(samples, "__len__") and len(samples) == 0):
+            return None
 
         buf = io.BytesIO()
         sf.write(buf, samples, sample_rate, format="WAV")