Prevent panic on merge to PR (#10403)

If you attempt to merge to a branch which on a PR there will be a nil pointer error in the pull request checker.

This panic is uncaught and will bring down the gitea server.

This PR adds protection to prevent this.

1 files changed, 8 insertions, 0 deletions

diff --git a/services/pull/pull.go b/services/pull/pull.go
index 6e51ad0a24..6af751856d 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -324,6 +324,10 @@ func PushToBaseRepo(pr *models.PullRequest) (err error) {
 		}
 	}()
 
+	if err := pr.LoadHeadRepo(); err != nil {
+		log.Error("Unable to load head repository for PR[%d] Error: %v", pr.ID, err)
+		return err
+	}
 	headRepoPath := pr.HeadRepo.RepoPath()
 
 	if err := git.Clone(headRepoPath, tmpBasePath, git.CloneRepoOptions{
@@ -340,6 +344,10 @@ func PushToBaseRepo(pr *models.PullRequest) (err error) {
 		return fmt.Errorf("OpenRepository: %v", err)
 	}
 
+	if err := pr.LoadBaseRepo(); err != nil {
+		log.Error("Unable to load base repository for PR[%d] Error: %v", pr.ID, err)
+		return err
+	}
 	if err := gitRepo.AddRemote("base", pr.BaseRepo.RepoPath(), false); err != nil {
 		return fmt.Errorf("tmpGitRepo.AddRemote: %v", err)
 	}