ipc/server: Fix an issue where the dispatcher errors were not being correctly unmarshalled from the response.  This is because we need a concrete type to unmarshal into.
ipc/server: Fix an issue where the dispatcher errors were not being
correctly unmarshalled from the response.  This is because we need a
concrete type to unmarshal into.

Change-Id: Icbc4c7af26c0cf639e04c2808094824f248d4b2f

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref