more typing improvements

nicegui/background_tasks.py

@@ -1,4 +1,4 @@
-'''inspired from https://quantlane.com/blog/ensure-asyncio-task-exceptions-get-logged/'''
+"""inspired from https://quantlane.com/blog/ensure-asyncio-task-exceptions-get-logged/"""
 import asyncio
 import sys
 from typing import Awaitable, Dict, Set, TypeVar
@@ -15,12 +15,12 @@ lazy_tasks_waiting: Dict[str, Awaitable[T]] = {}
 
 
 def create(coroutine: Awaitable[T], *, name: str = 'unnamed task') -> 'asyncio.Task[T]':
-    '''Wraps a loop.create_task call and ensures there is an exception handler added to the task.
+    """Wraps a loop.create_task call and ensures there is an exception handler added to the task.
 
     If the task raises an exception, it is logged and handled by the global exception handlers.
     Also a reference to the task is kept until it is done, so that the task is not garbage collected mid-execution.
     See https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task.
-    '''
+    """
     task = globals.loop.create_task(coroutine, name=name) if name_supported else globals.loop.create_task(coroutine)
     task.add_done_callback(_handle_task_result)
     running_tasks.add(task)
@@ -28,11 +28,11 @@ def create(coroutine: Awaitable[T], *, name: str = 'unnamed task') -> 'asyncio.T
     return task
 
 
-def create_lazy(coroutine: Awaitable[T], *, name: str) -> 'asyncio.Task[T]':
-    '''Wraps a create call and ensures a second task with the same name is delayed until the first one is done.
+def create_lazy(coroutine: Awaitable[T], *, name: str) -> None:
+    """Wraps a create call and ensures a second task with the same name is delayed until the first one is done.
 
     If a third task with the same name is created while the first one is still running, the second one is discarded.
-    '''
+    """
     if name in lazy_tasks_running:
         lazy_tasks_waiting[name] = coroutine
         return

nicegui/elements/scene.py

@@ -7,7 +7,6 @@ from ..element import Element
 from ..events import SceneClickEventArguments, SceneClickHit, handle_event
 from ..helpers import KWONLY_SLOTS
 from .scene_object3d import Object3D
-from .scene_objects import Scene as SceneObject
 
 register_component('scene', __file__, 'scene.js', [
     'lib/three.min.js',

nicegui/events.py

@@ -276,7 +276,7 @@ def handle_event(handler: Optional[Callable],
             return
         no_arguments = not signature(handler).parameters
         sender = arguments.sender if isinstance(arguments, EventArguments) else sender
-        assert sender.parent_slot is not None
+        assert sender is not None and sender.parent_slot is not None
         with sender.parent_slot:
             result = handler() if no_arguments else handler(arguments)
         if is_coroutine(handler):