Refactor error handling (#308)

use fmt instead of log

log.Fatal -> return err

set non-zero exit code on error

print to default err log

cleanup

fix vet

Co-authored-by: Norwin Roosen <git@nroo.de>
Co-authored-by: 6543 <6543@obermui.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/308
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: 6543 <6543@obermui.de>
Co-Authored-By: Norwin <noerw@noreply.gitea.io>
Co-Committed-By: Norwin <noerw@noreply.gitea.io>

cmd/organizations.go

@@ -5,7 +5,7 @@
 package cmd
 
 import (
-	"log"
+	"fmt"
 
 	"code.gitea.io/tea/cmd/organizations"
 
@@ -34,7 +34,5 @@ func runOrganizations(ctx *cli.Context) error {
 }
 
 func runOrganizationDetail(path string) error {
-
-	log.Fatal("Not yet implemented.")
-	return nil
+	return fmt.Errorf("Not yet implemented")
 }