agent: error when user record is not in database (#1303)

src/Simplex/Messaging/Agent/Client.hs

@@ -1930,6 +1930,7 @@ withStoreBatch' c actions = withStoreBatch c (fmap (fmap Right) . actions)
 storeError :: StoreError -> AgentErrorType
 storeError = \case
   SEConnNotFound -> CONN NOT_FOUND
+  SEUserNotFound -> NO_USER
   SERatchetNotFound -> CONN NOT_FOUND
   SEConnDuplicate -> CONN DUPLICATE
   SEBadConnType CRcv -> CONN SIMPLEX

src/Simplex/Messaging/Agent/Protocol.hs

@@ -1338,6 +1338,8 @@ data AgentErrorType
     CMD {cmdErr :: CommandErrorType, errContext :: String}
   | -- | connection errors
     CONN {connErr :: ConnectionErrorType}
+  | -- | user not found in database
+    NO_USER
   | -- | SMP protocol errors forwarded to agent clients
     SMP {serverAddress :: String, smpErr :: ErrorType}
   | -- | NTF protocol errors forwarded to agent clients