task: start TaskObserver when tasks can be created

We have to start proxy observer tasks once we know the TaskManager has an event
loop.

src/pipecat/pipeline/task.py

@@ -173,7 +173,7 @@ class PipelineTask(BaseTask):
         if self.has_finished():
             return
         try:
-            push_task = self._create_tasks()
+            push_task = await self._create_tasks()
             await self._task_manager.wait_for_task(push_task)
         except asyncio.CancelledError:
             # We are awaiting on the push task and it might be cancelled
@@ -203,7 +203,7 @@ class PipelineTask(BaseTask):
             for frame in frames:
                 await self.queue_frame(frame)
 
-    def _create_tasks(self):
+    async def _create_tasks(self):
         self._process_up_task = self._task_manager.create_task(
             self._process_up_queue(), f"{self}::_process_up_queue"
         )
@@ -214,6 +214,8 @@ class PipelineTask(BaseTask):
             self._process_push_queue(), f"{self}::_process_push_queue"
         )
 
+        await self._observer.start()
+
         return self._process_push_task
 
     def _maybe_start_heartbeat_tasks(self):

src/pipecat/pipeline/task_observer.py

@@ -58,8 +58,9 @@ class TaskObserver(BaseObserver):
     def __init__(self, *, observers: List[BaseObserver] = [], task_manager: TaskManager):
         self._id: int = obj_id()
         self._name: str = f"{self.__class__.__name__}#{obj_count(self)}"
-        self._proxies: List[Proxy] = self._create_proxies(observers)
+        self._observers = observers
         self._task_manager = task_manager
+        self._proxies: List[Proxy] = []
 
     @property
     def id(self) -> int:
@@ -69,6 +70,10 @@ class TaskObserver(BaseObserver):
     def name(self) -> str:
         return self._name
 
+    async def start(self):
+        """Starts all proxy observer tasks."""
+        self._proxies = self._create_proxies(self._observers)
+
     async def stop(self):
         """Stops all proxy observer tasks."""
         for proxy in self._proxies: