core: do not create decryption error chat items for earlier messages (#2189)

* core: do not create decryption error chat items for earlier messages

* do not report earlier error, mobile items, fix tests

src/Simplex/Chat.hs

@@ -2820,19 +2820,19 @@ processAgentMessageConn user@User {userId} corrId agentConnId agentMessage = do
     agentMsgDecryptError :: AgentErrorType -> Maybe (MsgDecryptError, Word32)
     agentMsgDecryptError = \case
       AGENT (A_CRYPTO RATCHET_HEADER) -> Just (MDERatchetHeader, 1)
-      AGENT (A_CRYPTO (RATCHET_EARLIER n)) -> Just (MDEEarlier, n + 1) -- 1 is added to account for the message that has A_DUPLICATE error
       AGENT (A_CRYPTO (RATCHET_SKIPPED n)) -> Just (MDETooManySkipped, n)
       -- we are not treating this as decryption error, as in many cases it happens as the result of duplicate or redundant delivery,
       -- and we don't have a way to differentiate.
       -- we could store the hashes of past messages in the agent, or delaying message deletion after ACK
       -- A_DUPLICATE -> Nothing
+      -- earlier messages may be received in case of redundant delivery, and do not necessarily indicate an error
+      -- AGENT (A_CRYPTO (RATCHET_EARLIER n)) -> Nothing
       _ -> Nothing
 
     mdeUpdatedCI :: (MsgDecryptError, Word32) -> CChatItem c -> Maybe (ChatItem c 'MDRcv, CIContent 'MDRcv)
     mdeUpdatedCI (mde', n') (CChatItem _ ci@ChatItem {content = CIRcvDecryptionError mde n})
       | mde == mde' = case mde of
         MDERatchetHeader -> r (n + n')
-        MDEEarlier -> r n -- the first error in a sequence has the largest number – it's the number of messages to receive to catch up, keeping it
         MDETooManySkipped -> r n' -- the numbers are not added as sequential MDETooManySkipped will have it incremented by 1
       | otherwise = Nothing
       where

src/Simplex/Chat/Messages.hs

@@ -735,10 +735,7 @@ data CIContent (d :: MsgDirection) where
 
 deriving instance Show (CIContent d)
 
-data MsgDecryptError
-  = MDERatchetHeader
-  | MDEEarlier
-  | MDETooManySkipped
+data MsgDecryptError = MDERatchetHeader | MDETooManySkipped
   deriving (Eq, Show, Generic)
 
 instance ToJSON MsgDecryptError where
@@ -954,7 +951,6 @@ msgDecryptErrorText err n =
   where
     errName = case err of
       MDERatchetHeader -> "header"
-      MDEEarlier -> "earlier message"
       MDETooManySkipped -> "too many skipped messages"
 
 msgDirToModeratedContent_ :: SMsgDirection d -> CIContent d