From 49b98e45bc6301b74181282a410aa02d8e0b8f30 Mon Sep 17 00:00:00 2001
From: Nanguan Lin <70063547+lng2020@users.noreply.github.com>
Date: Tue, 5 Dec 2023 16:29:43 +0800
Subject: [PATCH] Fix migration panic due to an empty review comment diff
 (#28334)

Fix #28328
```
func (p *PullRequestComment) GetDiffHunk() string {
	if p == nil || p.DiffHunk == nil {
		return ""
	}
	return *p.DiffHunk
}
```
This function in the package `go-github` may return an empty diff. When
it's empty, the following code will panic because it access `ss[1]`

https://github.com/go-gitea/gitea/blob/ec1feedbf582b05b6a5e8c59fb2457f25d053ba2/services/migrations/gitea_uploader.go#L861-L867

https://github.com/go-gitea/gitea/blob/ec1feedbf582b05b6a5e8c59fb2457f25d053ba2/modules/git/diff.go#L97-L101
---
 services/migrations/gitea_uploader.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/services/migrations/gitea_uploader.go b/services/migrations/gitea_uploader.go
index ddc2cbd4ec832..6ad0a2326bd16 100644
--- a/services/migrations/gitea_uploader.go
+++ b/services/migrations/gitea_uploader.go
@@ -862,7 +862,7 @@ func (g *GiteaLocalUploader) CreateReviews(reviews ...*base.Review) error {
 			line := comment.Line
 			if line != 0 {
 				comment.Position = 1
-			} else {
+			} else if comment.DiffHunk != "" {
 				_, _, line, _ = git.ParseDiffHunkString(comment.DiffHunk)
 			}