Teensie `piker.data` styling tweaks

- use more compact optional value style with `|`-union
- fix `.flows` typing-only import since we need `MktPair` to be
  immediately defined for use on a `msgspec.Struct` field.
- more "tree-like" warning msg in `.validate()` reporting.

piker/data/_web_bs.py

@@ -273,7 +273,7 @@ async def _reconnect_forever(
                 nobsws._connected.set()
                 await trio.sleep_forever()
         except HandshakeError:
-            log.exception(f'Retrying connection')
+            log.exception('Retrying connection')
 
         # ws & nursery block ends
 
@@ -359,8 +359,8 @@ async def open_autorecon_ws(
 
 
 '''
-JSONRPC response-request style machinery for transparent multiplexing of msgs
-over a NoBsWs.
+JSONRPC response-request style machinery for transparent multiplexing
+of msgs over a `NoBsWs`.
 
 '''
 
@@ -377,43 +377,82 @@ async def open_jsonrpc_session(
     url: str,
     start_id: int = 0,
     response_type: type = JSONRPCResult,
-    request_type: Optional[type] = None,
-    request_hook: Optional[Callable] = None,
-    error_hook: Optional[Callable] = None,
+    msg_recv_timeout: float = float('inf'),
+    # ^NOTE, since only `deribit` is using this jsonrpc stuff atm
+    # and options mkts are generally "slow moving"..
+    #
+    # FURTHER if we break the underlying ws connection then since we
+    # don't pass a `fixture` to the task that manages `NoBsWs`, i.e.
+    # `_reconnect_forever()`, the jsonrpc "transport pipe" get's
+    # broken and never restored with wtv init sequence is required to
+    # re-establish a working req-resp session.
+
 ) -> Callable[[str, dict], dict]:
+    '''
+    Init a json-RPC-over-websocket connection to the provided `url`.
+
+    A `json_rpc: Callable[[str, dict], dict` is delivered to the
+    caller for sending requests and a bg-`trio.Task` handles
+    processing of response msgs including error reporting/raising in
+    the parent/caller task.
+
+    '''
+    # NOTE, store all request msgs so we can raise errors on the
+    # caller side!
+    req_msgs: dict[int, dict] = {}
 
     async with (
-        trio.open_nursery() as n,
-        open_autorecon_ws(url) as ws
+        trio.open_nursery() as tn,
+        open_autorecon_ws(
+            url=url,
+            msg_recv_timeout=msg_recv_timeout,
+        ) as ws
     ):
-        rpc_id: Iterable = count(start_id)
+        rpc_id: Iterable[int] = count(start_id)
         rpc_results: dict[int, dict] = {}
 
-        async def json_rpc(method: str, params: dict) -> dict:
+        async def json_rpc(
+            method: str,
+            params: dict,
+        ) -> dict:
             '''
             perform a json rpc call and wait for the result, raise exception in
             case of error field present on response
             '''
+            nonlocal req_msgs
+
+            req_id: int = next(rpc_id)
             msg = {
                 'jsonrpc': '2.0',
-                'id': next(rpc_id),
+                'id': req_id,
                 'method': method,
                 'params': params
             }
             _id = msg['id']
 
-            rpc_results[_id] = {
+            result = rpc_results[_id] = {
                 'result': None,
-                'event': trio.Event()
+                'error': None,
+                'event': trio.Event(),  # signal caller resp arrived
             }
+            req_msgs[_id] = msg
 
             await ws.send_msg(msg)
 
+            # wait for reponse before unblocking requester code
             await rpc_results[_id]['event'].wait()
 
-            ret = rpc_results[_id]['result']
+            if (maybe_result := result['result']):
+                ret = maybe_result
+                del rpc_results[_id]
 
-            del rpc_results[_id]
+            else:
+                err = result['error']
+                raise Exception(
+                    f'JSONRPC request failed\n'
+                    f'req: {msg}\n'
+                    f'resp: {err}\n'
+                )
 
             if ret.error is not None:
                 raise Exception(json.dumps(ret.error, indent=4))
@@ -428,6 +467,7 @@ async def open_jsonrpc_session(
             the server side.
 
             '''
+            nonlocal req_msgs
             async for msg in ws:
                 match msg:
                     case {
@@ -451,19 +491,28 @@ async def open_jsonrpc_session(
                         'params': _,
                     }:
                         log.debug(f'Recieved\n{msg}')
-                        if request_hook:
-                            await request_hook(request_type(**msg))
 
                     case {
                         'error': error
                     }:
-                        log.warning(f'Recieved\n{error}')
-                        if error_hook:
-                            await error_hook(response_type(**msg))
+                        # retreive orig request msg, set error
+                        # response in original "result" msg,
+                        # THEN FINALLY set the event to signal caller
+                        # to raise the error in the parent task.
+                        req_id: int = error['id']
+                        req_msg: dict = req_msgs[req_id]
+                        result: dict = rpc_results[req_id]
+                        result['error'] = error
+                        result['event'].set()
+                        log.error(
+                            f'JSONRPC request failed\n'
+                            f'req: {req_msg}\n'
+                            f'resp: {error}\n'
+                        )
 
                     case _:
                         log.warning(f'Unhandled JSON-RPC msg!?\n{msg}')
 
-        n.start_soon(recv_task)
+        tn.start_soon(recv_task)
         yield json_rpc
-        n.cancel_scope.cancel()
+        tn.cancel_scope.cancel()