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

)

## Description



closes: #XXXX

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

- [ ] 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 {