chore!: remove x/slashing legacy querier (#12581)

Author: alexanderbez

CHANGELOG.md

@@ -62,6 +62,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking Changes
 
+* (x/slashing) [#12581](https://github.com/cosmos/cosmos-sdk/pull/12581) Remove `x/slashing` legacy querier.
 * (types) [\#12355](https://github.com/cosmos/cosmos-sdk/pull/12355) Remove the compile-time `types.DBbackend` variable. Removes usage of the same in server/util.go
 * (x/gov) [#12368](https://github.com/cosmos/cosmos-sdk/pull/12369) Gov keeper is now passed by reference instead of copy to make post-construction mutation of Hooks and Proposal Handlers possible at a framework level.
 * (simapp) [#12270](https://github.com/cosmos/cosmos-sdk/pull/12270) Remove `invCheckPeriod uint` attribute from `SimApp` struct as per migration of `x/crisis` to app wiring

x/slashing/keeper/querier.go

@@ -140,7 +140,9 @@ func (AppModule) QuerierRoute() string {
 
 // LegacyQuerierHandler returns the slashing module sdk.Querier.
 func (am AppModule) LegacyQuerierHandler(legacyQuerierCdc *codec.LegacyAmino) sdk.Querier {
-	return keeper.NewQuerier(am.keeper, legacyQuerierCdc)
+	return func(sdk.Context, []string, abci.RequestQuery) ([]byte, error) {
+		return nil, fmt.Errorf("legacy querier not supported for the x/%s module", types.ModuleName)
+	}
 }
 
 // RegisterServices registers module services.