fix: add nil checks for controller and host keeper services (#2308)

## Description



closes: #XXXX

---

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- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

CHANGELOG.md

@@ -105,6 +105,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (27-interchain-accounts) [\#2308](https://github.com/cosmos/ibc-go/pull/2308) Nil checks have been added to ensure services are not registered for nil host or controller keepers.
 * (makefile) [\#1785](https://github.com/cosmos/ibc-go/pull/1785) Fetch the correct versions of protocol buffers dependencies from tendermint, cosmos-sdk, and ics23.
 * (light-clients/solomachine) [#1839](https://github.com/cosmos/ibc-go/issues/1839) Fixed usage of the new diversifier in validation of changing diversifiers for the solo machine. The current diversifier must sign over the new diversifier.
 * (light-clients/07-tendermint) [\#1674](https://github.com/cosmos/ibc-go/pull/1674) Submitted ClientState is zeroed out before checking the proof in order to prevent the proposal from containing information governance is not actually voting on.

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

@@ -22,19 +22,21 @@ func NewMigrator(keeper *Keeper) Migrator {
 // AssertChannelCapabilityMigrations checks that all channel capabilities generated using the interchain accounts controller port prefix
 // are owned by the controller submodule and ibc.
 func (m Migrator) AssertChannelCapabilityMigrations(ctx sdk.Context) error {
-	for _, ch := range m.keeper.GetAllActiveChannels(ctx) {
-		name := host.ChannelCapabilityPath(ch.PortId, ch.ChannelId)
-		cap, found := m.keeper.scopedKeeper.GetCapability(ctx, name)
-		if !found {
-			return sdkerrors.Wrapf(capabilitytypes.ErrCapabilityNotFound, "failed to find capability: %s", name)
+	if m.keeper != nil {
+		for _, ch := range m.keeper.GetAllActiveChannels(ctx) {
+			name := host.ChannelCapabilityPath(ch.PortId, ch.ChannelId)
+			cap, found := m.keeper.scopedKeeper.GetCapability(ctx, name)
+			if !found {
+				return sdkerrors.Wrapf(capabilitytypes.ErrCapabilityNotFound, "failed to find capability: %s", name)
+			}
+
+			isAuthenticated := m.keeper.scopedKeeper.AuthenticateCapability(ctx, cap, name)
+			if !isAuthenticated {
+				return sdkerrors.Wrapf(capabilitytypes.ErrCapabilityNotOwned, "expected capability owner: %s", types.SubModuleName)
+			}
+
+			m.keeper.SetMiddlewareEnabled(ctx, ch.PortId, ch.ChannelId)
 		}
-
-		isAuthenticated := m.keeper.scopedKeeper.AuthenticateCapability(ctx, cap, name)
-		if !isAuthenticated {
-			return sdkerrors.Wrapf(capabilitytypes.ErrCapabilityNotOwned, "expected capability owner: %s", types.SubModuleName)
-		}
-
-		m.keeper.SetMiddlewareEnabled(ctx, ch.PortId, ch.ChannelId)
 	}
 
 	return nil

modules/apps/27-interchain-accounts/module.go

@@ -76,6 +76,7 @@ func (AppModuleBasic) RegisterGRPCGatewayRoutes(clientCtx client.Context, mux *r
 	if err != nil {
 		panic(err)
 	}
+
 	err = hosttypes.RegisterQueryHandlerClient(context.Background(), mux, hosttypes.NewQueryClient(clientCtx))
 	if err != nil {
 		panic(err)
@@ -150,9 +151,14 @@ func (am AppModule) LegacyQuerierHandler(legacyQuerierCdc *codec.LegacyAmino) sd
 
 // RegisterServices registers module services
 func (am AppModule) RegisterServices(cfg module.Configurator) {
-	controllertypes.RegisterMsgServer(cfg.MsgServer(), controllerkeeper.NewMsgServerImpl(am.controllerKeeper))
-	controllertypes.RegisterQueryServer(cfg.QueryServer(), am.controllerKeeper)
-	hosttypes.RegisterQueryServer(cfg.QueryServer(), am.hostKeeper)
+	if am.controllerKeeper != nil {
+		controllertypes.RegisterMsgServer(cfg.MsgServer(), controllerkeeper.NewMsgServerImpl(am.controllerKeeper))
+		controllertypes.RegisterQueryServer(cfg.QueryServer(), am.controllerKeeper)
+	}
+
+	if am.hostKeeper != nil {
+		hosttypes.RegisterQueryServer(cfg.QueryServer(), am.hostKeeper)
+	}
 
 	m := controllerkeeper.NewMigrator(am.controllerKeeper)
 	if err := cfg.RegisterMigration(types.ModuleName, 1, m.AssertChannelCapabilityMigrations); err != nil {