log error in cli (#6976)

* log error in cli

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

* write to stderr

* Update ocis/cmd/ocis/main.go

Co-authored-by: Andre Duffeck <aduffeck@users.noreply.github.com>

---------

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>
Co-authored-by: Andre Duffeck <aduffeck@users.noreply.github.com>

ocis/cmd/ocis/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/owncloud/ocis/v2/ocis/pkg/command"
@@ -8,6 +9,7 @@ import (
 
 func main() {
 	if err := command.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
 		os.Exit(1)
 	}
 }