plugin XEP-0384: proper handling of exceptions in prepare_for_profile

sat/plugins/plugin_xep_0384.py

@@ -1468,11 +1468,22 @@ class OMEMO:
             self.__session_manager_waiters[profile] = []
 
             # Build and store the session manager
-            session_manager = await prepare_for_profile(
-                self.__sat,
-                profile,
-                initial_own_label="Libervia"
-            )
+            try:
+                session_manager = await prepare_for_profile(
+                    self.__sat,
+                    profile,
+                    initial_own_label="Libervia"
+                )
+            except Exception as e:
+                # In case of an error during initalization, notify the waiters accordingly
+                # and delete them
+                for waiter in self.__session_manager_waiters[profile]:
+                    waiter.errback(e)
+                del self.__session_manager_waiters[profile]
+
+                # Re-raise the exception
+                raise
+
             self.__session_managers[profile] = session_manager
 
             # Notify the waiters and delete them