Squash various linter warnings (#5652)

Closes: #5651

server/export.go

@@ -24,7 +24,7 @@ const (
 )
 
 // ExportCmd dumps app state to JSON.
-func ExportCmd(ctx *Context, cdc *codec.Codec, appExporter AppExporter) *cobra.Command {
+func ExportCmd(ctx *Context, cdc codec.JSONMarshaler, appExporter AppExporter) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "export",
 		Short: "Export state to JSON",

server/util.go

@@ -118,7 +118,7 @@ func interceptLoadConfig() (conf *cfg.Config, err error) {
 
 // add server commands
 func AddCommands(
-	ctx *Context, cdc *codec.Codec,
+	ctx *Context, cdc codec.JSONMarshaler,
 	rootCmd *cobra.Command,
 	appCreator AppCreator, appExport AppExporter) {
 
@@ -154,7 +154,7 @@ func AddCommands(
 //
 // NOTE: The ordering of the keys returned as the resulting JSON message is
 // non-deterministic, so the client should not rely on key ordering.
-func InsertKeyJSON(cdc *codec.Codec, baseJSON []byte, key string, value json.RawMessage) ([]byte, error) {
+func InsertKeyJSON(cdc codec.JSONMarshaler, baseJSON []byte, key string, value json.RawMessage) ([]byte, error) {
 	var jsonMap map[string]json.RawMessage
 
 	if err := cdc.UnmarshalJSON(baseJSON, &jsonMap); err != nil {