replace log.Fatal/os.Exit with error returns (#941)

* Use stdlib encoders
* Reduce some duplication
* Remove global pagination state
* Dedupe JSON detail types
* Bump golangci-lint

Reviewed-on: https://gitea.com/gitea/tea/pulls/941
Co-authored-by: techknowlogick <techknowlogick@gitea.com>
Co-committed-by: techknowlogick <techknowlogick@gitea.com>

modules/config/login.go

@@ -164,18 +164,17 @@ func SetDefaultLogin(name string) error {
 }
 
 // GetLoginByName get login by name (case insensitive)
-func GetLoginByName(name string) *Login {
-	err := loadConfig()
-	if err != nil {
-		log.Fatal(err)
+func GetLoginByName(name string) (*Login, error) {
+	if err := loadConfig(); err != nil {
+		return nil, err
 	}
 
-	for _, l := range config.Logins {
-		if strings.EqualFold(l.Name, name) {
-			return &l
+	for i := range config.Logins {
+		if strings.EqualFold(config.Logins[i].Name, name) {
+			return &config.Logins[i], nil
 		}
 	}
-	return nil
+	return nil, nil
 }
 
 // GetLoginByToken get login by token