Attempt to satisfy mypy (plus cleaner approach).

backend/chainlit/element.py

@@ -57,6 +57,8 @@ class ElementDict(TypedDict):
 
 @dataclass
 class Element:
+ # Thread id
+ thread_id: str = Field(default_factory=lambda: context.session.thread_id)
  # The type of the element. This will be used to determine how to display the element in the UI.
  type: ClassVar[ElementType]
  # Name of the element, this will be used to reference the element in the UI.
@@ -83,15 +85,11 @@ class Element:
  language: Optional[str] = None
  # Mime type, infered based on content if not provided
  mime: Optional[str] = None
- # Thread id
- thread_id: Optional[str] = None
 
  def __post_init__(self) -> None:
  trace_event(f"init {self.__class__.__name__}")
  self.persisted = False
  self.updatable = False
- if not self.thread_id:
- self.thread_id = context.session.thread_id
 
  if not self.url and not self.path and not self.content:
  raise ValueError("Must provide url, path or content to instantiate element")