fix(exomint): stateful validation add

x/exomint/client/cli/tx.go

@@ -50,10 +50,7 @@ func CmdUpdateParams() *cobra.Command {
 				return err
 			}
 
-			msg, err := newBuildUpdateParamsMsg(clientCtx, cmd.Flags())
-			if err != nil {
-				return err
-			}
+			msg := newBuildUpdateParamsMsg(clientCtx, cmd.Flags())
 
 			// this calls ValidateBasic internally so we don't need to do that.
 			return tx.GenerateOrBroadcastTxWithFactory(clientCtx, txf, msg)
@@ -79,7 +76,7 @@ func CmdUpdateParams() *cobra.Command {
 
 func newBuildUpdateParamsMsg(
 	clientCtx client.Context, fs *pflag.FlagSet,
-) (*types.MsgUpdateParams, error) {
+) *types.MsgUpdateParams {
 	sender := clientCtx.GetFromAddress()
 	// #nosec G703 // this only errors if the flag isn't defined.
 	mintDenom, _ := fs.GetString(FlagMintDenom)
@@ -99,5 +96,5 @@ func newBuildUpdateParamsMsg(
 			EpochIdentifier: epochIdentifier,
 		},
 	}
-	return msg, nil
+	return msg
 }

x/exomint/keeper/msg_server.go

@@ -52,6 +52,15 @@ func (k Keeper) UpdateParams(
 		logger.Info("UpdateParams", "overriding EpochIdentifier with value", prevParams.EpochIdentifier)
 		nextParams.EpochIdentifier = prevParams.EpochIdentifier
 	}
+	// stateful validations
+	// no need to check if MintDenom is registered in BankKeeper, since it does not
+	// itself perform such checks.
+	// the reward is already guaranteed to be positive and fits in the bit length.
+	// we just have to check epoch here.
+	if _, found := k.epochsKeeper.GetEpochInfo(c, nextParams.EpochIdentifier); !found {
+		logger.Info("UpdateParams", "overriding EpochIdentifier with value", prevParams.EpochIdentifier)
+		nextParams.EpochIdentifier = prevParams.EpochIdentifier
+	}
 	k.SetParams(c, msg.Params)
 	return nil, nil
 }