Swagger info corrections (#9441)

* use numbers and not http.Status___ enum

* fix test

* add many missing swagger responses

* code format

* Deletion Sould return 204 ...

* error handling improvements

* if special error type ... then add it to swagger too

* one smal nit

* invalidTopicsError is []string

* valid swagger specification 2.0
 - if you add responses swagger can tell you if you do it right 👍

* use ctx.InternalServerError

* Revert "use numbers and not http.Status___ enum"

This reverts commit b1ff386e24.

* use http.Status* enum everywhere

routers/api/v1/repo/subscriber.go

@@ -5,6 +5,8 @@
 package repo
 
 import (
+	"net/http"
+
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/convert"
 	api "code.gitea.io/gitea/modules/structs"
@@ -31,14 +33,15 @@ func ListSubscribers(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/UserList"
+
 	subscribers, err := ctx.Repo.Repository.GetWatchers(0)
 	if err != nil {
-		ctx.Error(500, "GetWatchers", err)
+		ctx.Error(http.StatusInternalServerError, "GetWatchers", err)
 		return
 	}
 	users := make([]*api.User, len(subscribers))
 	for i, subscriber := range subscribers {
 		users[i] = convert.ToUser(subscriber, ctx.IsSigned, ctx.User != nil && ctx.User.IsAdmin)
 	}
-	ctx.JSON(200, users)
+	ctx.JSON(http.StatusOK, users)
 }