fix: Task exception was never retrieved if return annotation validation fails

src/sheppy/utils/task_execution.py

@@ -79,7 +79,15 @@ async def execute_task(__task: "Task", worker_id: str) -> tuple[Exception | None
         except Exception as e:
             raise Exception("Middleware error") from e
 
-        return exception, task.create_task()
+        # result validation might fail
+        try:
+            final_task = task.create_task()
+        except Exception as e:
+            task = await TaskProcessor.handle_failed_task(task, e)
+            exception = e
+            final_task = task.create_task()
+
+        return exception, final_task
 
     @staticmethod
     async def process_pre_task_middleware(task: TaskInternal) -> tuple[TaskInternal, list[Any]]:
@@ -123,6 +131,7 @@ def handle_success_and_update_task_metadata(task: TaskInternal, result: Any, wor
     @staticmethod
     async def handle_failed_task(task: TaskInternal, exception: Exception) -> TaskInternal:
         task.completed = False
+        task.result = None
         task.error = f"{exception.__class__.__name__}: {exception}"
 
         if task.is_retriable:

tests/contract/test_edgecases.py

@@ -0,0 +1,18 @@
+from sheppy import Queue, Worker, task
+from sheppy.testqueue import assert_is_failed
+
+
+@task
+async def task_with_wrong_return_annotation() -> list:
+    return 5
+
+
+async def test_wrong_return_annotation(queue: Queue, worker: Worker) -> None:
+    t = task_with_wrong_return_annotation()
+
+    await queue.add(t)
+    await worker.work(1)
+
+    t = await queue.get_task(t)
+
+    assert_is_failed(t)