enhance: Improve validation errors for secrets/variables (#39221)

Signed-off-by: Ross Golder <ross@golder.org>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/context/upload/upload.go

@@ -15,6 +15,7 @@ import (
 	"gitea.dev/modules/log"
 	"gitea.dev/modules/reqctx"
 	"gitea.dev/modules/setting"
+	"gitea.dev/modules/util"
 	"gitea.dev/services/context"
 )
 
@@ -33,6 +34,10 @@ func (err ErrFileTypeForbidden) Error() string {
 	return "This file cannot be uploaded or modified due to a forbidden file extension or type."
 }
 
+func (err ErrFileTypeForbidden) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
 var wildcardTypeRe = regexp.MustCompile(`^[a-z]+/\*$`)
 
 // Verify validates whether a file is allowed to be uploaded. If buf is empty, it will just check if the file