Test nil key and adapt docs

x/wasm/internal/keeper/keeper.go

@@ -421,7 +421,7 @@ func (k Keeper) QuerySmart(ctx sdk.Context, contractAddr sdk.AccAddress, req []b
 	return queryResult, nil
 }
 
-// QueryRaw returns the contract's state for give key. For a `nil` key a empty slice result is returned.
+// QueryRaw returns the contract's state for give key. Returns `nil` when key is `nil`.
 func (k Keeper) QueryRaw(ctx sdk.Context, contractAddress sdk.AccAddress, key []byte) []byte {
 	if key == nil {
 		return nil

x/wasm/internal/keeper/querier_test.go

@@ -104,6 +104,12 @@ func TestQueryContractState(t *testing.T) {
 		},
 		"query empty raw key": {
 			srcPath: []string{QueryGetContractState, addr.String(), QueryMethodContractStateRaw},
+			srcReq:  abci.RequestQuery{Data: []byte("")},
+			expRes:  nil,
+		},
+		"query nil raw key": {
+			srcPath: []string{QueryGetContractState, addr.String(), QueryMethodContractStateRaw},
+			srcReq:  abci.RequestQuery{Data: nil},
 			expRes:  nil,
 		},
 		"query raw with unknown address": {