fix: add type hints for App model and improve error handling in audio services (#12677)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/services/audio_service.py

@@ -82,7 +82,7 @@ class AudioService:
         from app import app
         from extensions.ext_database import db
 
-        def invoke_tts(text_content: str, app_model, voice: Optional[str] = None):
+        def invoke_tts(text_content: str, app_model: App, voice: Optional[str] = None):
             with app.app_context():
                 if app_model.mode in {AppMode.ADVANCED_CHAT.value, AppMode.WORKFLOW.value}:
                     workflow = app_model.workflow
@@ -95,6 +95,8 @@ class AudioService:
 
                     voice = features_dict["text_to_speech"].get("voice") if voice is None else voice
                 else:
+                    if app_model.app_model_config is None:
+                        raise ValueError("AppModelConfig not found")
                     text_to_speech_dict = app_model.app_model_config.text_to_speech_dict
 
                     if not text_to_speech_dict.get("enabled"):