Mark TemplateLoading error as "UnprocessableEntity" (go-gitea#19445)

- Backport go-gitea#19445
  - Don't return Internal Server error if the user provide incorrect label template, instead return UnprocessableEntity.
  - Resolves go-gitea#19399

routers/api/v1/repo/repo.go

@@ -21,6 +21,7 @@ import (
 	"code.gitea.io/gitea/modules/convert"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
+	repo_module "code.gitea.io/gitea/modules/repository"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/util"
@@ -160,7 +161,7 @@ func Search(ctx *context.APIContext) {
 		opts.Collaborate = util.OptionalBoolFalse
 	}
 
-	var mode = ctx.FormString("mode")
+	mode := ctx.FormString("mode")
 	switch mode {
 	case "source":
 		opts.Fork = util.OptionalBoolFalse
@@ -186,9 +187,9 @@ func Search(ctx *context.APIContext) {
 		opts.IsPrivate = util.OptionalBoolOf(ctx.FormBool("is_private"))
 	}
 
-	var sortMode = ctx.FormString("sort")
+	sortMode := ctx.FormString("sort")
 	if len(sortMode) > 0 {
-		var sortOrder = ctx.FormString("order")
+		sortOrder := ctx.FormString("order")
 		if len(sortOrder) == 0 {
 			sortOrder = "asc"
 		}
@@ -264,7 +265,8 @@ func CreateUserRepo(ctx *context.APIContext, owner *user_model.User, opt api.Cre
 		if repo_model.IsErrRepoAlreadyExist(err) {
 			ctx.Error(http.StatusConflict, "", "The repository with the same name already exists.")
 		} else if db.IsErrNameReserved(err) ||
-			db.IsErrNamePatternNotAllowed(err) {
+			db.IsErrNamePatternNotAllowed(err) ||
+			repo_module.IsErrIssueLabelTemplateLoad(err) {
 			ctx.Error(http.StatusUnprocessableEntity, "", err)
 		} else {
 			ctx.Error(http.StatusInternalServerError, "CreateRepository", err)