adds task_done_callback to each task

The task_done_callback function handles exceptions and emitting
a notification when the task has finished.

src/pydase/data_service/task_manager.py

@@ -97,6 +97,28 @@ class TaskManager:
 
             @wraps(method)
             def start_task(*args: Any, **kwargs: Any) -> None:
+                def task_done_callback(task: asyncio.Task, name: str) -> None:
+                    """Handles tasks that have finished.
+
+                    Removes a task from the tasks dictionary, calls the defined
+                    callbacks, and logs and re-raises exceptions."""
+
+                    # removing the finished task from the tasks i
+                    self.tasks.pop(name, None)
+
+                    # emit the notification that the task was stopped
+                    for callback in self.task_status_change_callbacks:
+                        callback(name, None)
+
+                    exception = task.exception()
+                    if exception is not None:
+                        # Handle the exception, or you can re-raise it.
+                        logger.error(
+                            f"Task '{name}' encountered an exception: "
+                            f"{type(exception).__name__}: {exception}"
+                        )
+                        raise exception
+
                 async def task(*args: Any, **kwargs: Any) -> None:
                     try:
                         await method(*args, **kwargs)
@@ -126,11 +148,18 @@ class TaskManager:
                         **kwargs,
                     }
 
+                    # creating the task and adding the task_done_callback which checks
+                    # if an exception has occured during the task execution
+                    task_object = self._loop.create_task(task(*args, **kwargs))
+                    task_object.add_done_callback(
+                        lambda task: task_done_callback(task, name)
+                    )
+
                     # Store the task and its arguments in the '__tasks' dictionary. The
                     # key is the name of the method, and the value is a dictionary
                     # containing the task object and the updated keyword arguments.
                     self.tasks[name] = {
-                        "task": self._loop.create_task(task(*args, **kwargs)),
+                        "task": task_object,
                         "kwargs": kwargs_updated,
                     }
 
@@ -142,14 +171,10 @@ class TaskManager:
 
             def stop_task() -> None:
                 # cancel the task
-                task = self.tasks.pop(name, None)
+                task = self.tasks.get(name, None)
                 if task is not None:
                     self._loop.call_soon_threadsafe(task["task"].cancel)
 
-                    # emit the notification that the task was stopped
-                    for callback in self.task_status_change_callbacks:
-                        callback(name, None)
-
             # create start and stop methods for each coroutine
             setattr(self.service, f"start_{name}", start_task)
             setattr(self.service, f"stop_{name}", stop_task)