BUG-858: Do not return null when no RPC is registered

Change-Id: I6f416440d6a497d17050a1971e9a1eb111483e7a
Signed-off-by: Robert Varga <rovarga@cisco.com>
(cherry picked from commit 89fe85007a73fe83d1d3ca52fc331d4e594493cf)
Merge "BUG-858: Do not return null when no RPC is registered" into stable/hydrogen