cmd/syncthing: Don't fail early on api setup error (fixes 7558) (#7591)

* cmd/syncthing: Don't fail early on api setup error (fixes 7558)

* switch to factory pattern

* refactor config command to show help on nothing

* wip

* wip

* already abort in before

cmd/syncthing/cli/errors.go

@@ -39,7 +39,7 @@ var errorsCommand = cli.Command{
 }
 
 func errorsPush(c *cli.Context) error {
-	client := c.App.Metadata["client"].(*APIClient)
+	client := c.App.Metadata["client"].(APIClient)
 	errStr := strings.Join(c.Args(), " ")
 	response, err := client.Post("system/error", strings.TrimSpace(errStr))
 	if err != nil {