feat: Add ErrorFrame emission to TTS/STT services for pipeline error detection (#2881)

* feat: Add ErrorFrame emission to TTS/STT services for pipeline error detection

- Add ErrorFrame emission to all major TTS/STT services during initialization and runtime failures
- Services updated: Cartesia, ElevenLabs, Deepgram, AssemblyAI, Rime, Azure
- ErrorFrame objects emitted with fatal=False for graceful degradation
- Enables on_pipeline_error event handler to detect service failures programmatically
- Add comprehensive pytest test suite to verify ErrorFrame emission
- Fixes issue where services failed gracefully but didn't emit ErrorFrame objects

This allows developers to implement real-time error monitoring and alerting
using the on_pipeline_error event handler introduced in v0.0.90.

* Update STT and TTS services to use consistent error handling pattern

- Improves error handling consistency across all services

* Add changelog entry for STT/TTS error handling improvements

* Linting issues Resolved

* Azure STT ErrorFrames added with consistent patterns

* Cartesia STT and Deepgram STT; additional fixes made

* Removed Fatal Flags across services, removed duplication

* Moving the changelog entry to the correct place.

* Refactoring some classes to use yield instead of push_error directly.

* Fixing ruff format.

---------

Co-authored-by: Filipi Fuchter <filipi87@gmail.com>

src/pipecat/services/lmnt/tts.py

@@ -223,7 +223,8 @@ class LmntTTSService(InterruptibleTTSService):
 
             await self._call_event_handler("on_connected")
         except Exception as e:
-            logger.error(f"{self} initialization error: {e}")
+            logger.error(f"{self} exception: {e}")
+            await self.push_error(ErrorFrame(error=f"{self} error: {e}"))
             self._websocket = None
             await self._call_event_handler("on_connection_error", f"{e}")
 
@@ -239,7 +240,8 @@ class LmntTTSService(InterruptibleTTSService):
                 # await self._websocket.send(json.dumps({"eof": True}))
                 await self._websocket.close()
         except Exception as e:
-            logger.error(f"{self} error closing websocket: {e}")
+            logger.error(f"{self} exception: {e}")
+            await self.push_error(ErrorFrame(error=f"{self} error: {e}"))
         finally:
             self._started = False
             self._websocket = None
@@ -276,7 +278,7 @@ class LmntTTSService(InterruptibleTTSService):
                         logger.error(f"{self} error: {msg['error']}")
                         await self.push_frame(TTSStoppedFrame())
                         await self.stop_all_metrics()
-                        await self.push_error(ErrorFrame(f"{self} error: {msg['error']}"))
+                        await self.push_error(ErrorFrame(error=f"{self} error: {msg['error']}"))
                         return
                 except json.JSONDecodeError:
                     logger.error(f"Invalid JSON message: {message}")
@@ -309,7 +311,8 @@ class LmntTTSService(InterruptibleTTSService):
                 await self._get_websocket().send(json.dumps({"flush": True}))
                 await self.start_tts_usage_metrics(text)
             except Exception as e:
-                logger.error(f"{self} error sending message: {e}")
+                logger.error(f"{self} exception: {e}")
+                yield ErrorFrame(error=f"{self} error: {e}")
                 yield TTSStoppedFrame()
                 await self._disconnect()
                 await self._connect()
@@ -317,3 +320,4 @@ class LmntTTSService(InterruptibleTTSService):
             yield None
         except Exception as e:
             logger.error(f"{self} exception: {e}")
+            yield ErrorFrame(error=f"{self} error: {e}")