fix: avoid panic when migrate param for newly added host

CHANGELOG.md

@@ -58,6 +58,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (core) [\#6055](https://github.com/cosmos/ibc-go/pull/6055) Introduce a new interface `ConsensusHost` used to validate an IBC `ClientState` and `ConsensusState` against the host chain's underlying consensus parameters.
 
 ### Bug Fixes
+* (apps/27-interchain-accounts) [\#6167](https://github.com/cosmos/ibc-go/pull/6167) Avoid panic when migrate param for newly added host.
 
 ## [v8.2.0](https://github.com/cosmos/ibc-go/releases/tag/v8.2.0) - 2024-04-05
 

modules/apps/27-interchain-accounts/host/keeper/migrations.go

@@ -21,9 +21,23 @@
 // MigrateParams migrates the host submodule's parameters from the x/params to self store.
 func (m Migrator) MigrateParams(ctx sdk.Context) error {
 	if m.keeper != nil {
+		defaultParams := types.DefaultParams()
 		var params types.Params
-		m.keeper.legacySubspace.GetParamSet(ctx, &params)
-
+		ps := &params
+		for _, pair := range ps.ParamSetPairs() {
+			if !m.keeper.legacySubspace.Has(ctx, pair.Key) {
+				var value interface{}
+				if string(pair.Key) == "HostEnabled" {
+					value = defaultParams.HostEnabled
+				} else if string(pair.Key) == "AllowMessages" {
+					value = defaultParams.AllowMessages
+				} else {
+					continue
+				}
+				m.keeper.legacySubspace.Set(ctx, pair.Key, value)
+			}
+			m.keeper.legacySubspace.Get(ctx, pair.Key, pair.Value)
+		}
 		if err := params.Validate(); err != nil {
 			return err
 		}

modules/apps/27-interchain-accounts/host/keeper/migrations_test.go

@@ -22,6 +22,11 @@ func (suite *KeeperTestSuite) TestMigratorMigrateParams() {
 			},
 			icahosttypes.DefaultParams(),
 		},
+		{
+			"success: no params",
+			func() {},
+			icahosttypes.DefaultParams(),
+		},
 	}
 
 	for _, tc := range testCases {

modules/apps/27-interchain-accounts/types/expected_keepers.go

@@ -37,4 +37,7 @@ type PortKeeper interface {
 // ParamSubspace defines the expected Subspace interface for module parameters.
 type ParamSubspace interface {
 	GetParamSet(ctx sdk.Context, ps paramtypes.ParamSet)
+	Has(ctx sdk.Context, key []byte) bool
+	Get(ctx sdk.Context, key []byte, ptr interface{})
+	Set(ctx sdk.Context, key []byte, value interface{})
 }