Add error suppress flag to `current_ipc_ctx()`

tractor/_state.py

@@ -124,9 +124,15 @@ _ctxvar_Context: ContextVar[Context] = ContextVar(
 )
 
 
-def current_ipc_ctx() -> Context:
+def current_ipc_ctx(
+    error_on_not_set: bool = False,
+) -> Context|None:
     ctx: Context = _ctxvar_Context.get()
-    if not ctx:
+
+    if (
+        not ctx
+        and error_on_not_set
+    ):
         from ._exceptions import InternalError
         raise InternalError(
             'No IPC context has been allocated for this task yet?\n'