plugin XEP-0115: Fix race condition on disco creation:

This patch chains disco query to `conn_deferred` to be sure that `client.disco` is set.

fix #484

libervia/backend/core/core_types.py

@@ -95,6 +95,8 @@ class SatXMPPEntity(ABC):
     discoHandler: disco.DiscoHandler
     messageProt: "SatMessageProtocol"
     identities: list[disco.DiscoIdentity]
+    # Fire when entity is connected
+    conn_deferred: defer.Deferred
     xmlstream: mod_xmlstream.XmlStream
     tor: "Tor | None" = None
 

libervia/backend/plugins/plugin_xep_0115.py

@@ -491,9 +491,13 @@ class XEP_0115_handler(XMPPHandler):
                     # Query the caps node to get disco info (XEP-0115 §6.2)
                     caps_node = f"{node}#{ver}" if node else ver
                     log.debug(f"Querying caps node {caps_node} for server {server_jid}")
-                    d = self.client.disco.requestInfo(
+                    # We chain to `conn_deferred` to avoid race condition and be sure that
+                    # we have `client.disco` set (see
+                    # https://www.goffi.org/tickets/view/484)
+                    d = self.client.conn_deferred
+                    d.addCallback(lambda __: self.client.disco.requestInfo(
                         server_jid, nodeIdentifier=caps_node
-                    )
+                    ))
                     d.addCallback(self._caps_node_cb, ver)
                     d.addErrback(self._caps_node_eb, server_jid, ver)