fix: prevent panic when GitLab release has more links than sources (#36295)

The code incorrectly assumed rel.Assets.Links and rel.Assets.Sources
arrays have equal length. This causes index out of bounds panic when
migrating GitLab releases with more links than sources, which is common
with GoReleaser-generated releases.

Fixes #36292

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/migration/release.go

@@ -10,9 +10,12 @@ import (
 
 // ReleaseAsset represents a release asset
 type ReleaseAsset struct {
-	ID            int64
-	Name          string
-	ContentType   *string `yaml:"content_type"`
+	ID   int64
+	Name string
+
+	// There was a field "ContentType (content_type)" because Some forges can provide that for assets,
+	// but we don't need it when migrating, so the field is omitted here.
+
 	Size          *int
 	DownloadCount *int `yaml:"download_count"`
 	Created       time.Time

services/migrations/github.go

@@ -329,7 +329,6 @@ func (g *GithubDownloaderV3) convertGithubRelease(ctx context.Context, rel *gith
 		r.Assets = append(r.Assets, &base.ReleaseAsset{
 			ID:            asset.GetID(),
 			Name:          asset.GetName(),
-			ContentType:   asset.ContentType,
 			Size:          asset.Size,
 			DownloadCount: asset.DownloadCount,
 			Created:       asset.CreatedAt.Time,

services/migrations/gitlab.go

@@ -316,12 +316,11 @@ func (g *GitlabDownloader) convertGitlabRelease(ctx context.Context, rel *gitlab
 
 	httpClient := NewMigrationHTTPClient()
 
-	for k, asset := range rel.Assets.Links {
+	for _, asset := range rel.Assets.Links {
 		assetID := asset.ID // Don't optimize this, for closure we need a local variable
 		r.Assets = append(r.Assets, &base.ReleaseAsset{
 			ID:            int64(asset.ID),
 			Name:          asset.Name,
-			ContentType:   &rel.Assets.Sources[k].Format,
 			Size:          &zero,
 			DownloadCount: &zero,
 			DownloadFunc: func() (io.ReadCloser, error) {

services/migrations/main_test.go

@@ -171,7 +171,6 @@ func assertReactionsEqual(t *testing.T, expected, actual []*base.Reaction) {
 func assertReleaseAssetEqual(t *testing.T, expected, actual *base.ReleaseAsset) {
 	assert.Equal(t, expected.ID, actual.ID)
 	assert.Equal(t, expected.Name, actual.Name)
-	assert.Equal(t, expected.ContentType, actual.ContentType)
 	assert.Equal(t, expected.Size, actual.Size)
 	assert.Equal(t, expected.DownloadCount, actual.DownloadCount)
 	assertTimeEqual(t, expected.Created, actual.Created)