Avoid panic caused by broken payload when creating commit status (#23216)

When creating commit status for Actons jobs, a payload with nil
`HeadCommit` will cause panic.

Reported at:
https://gitea.com/gitea/act_runner/issues/28#issuecomment-732166

Although the `HeadCommit` probably can not be nil after #23215,
`CreateCommitStatus` should protect itself, to avoid being broken in the
future.

In addition, it's enough to print error log instead of returning err
when `CreateCommitStatus` failed.

---------

Co-authored-by: delvh <dev.lh@web.de>

services/actions/commit_status.go

@@ -30,6 +30,16 @@ func CreateCommitStatus(ctx context.Context, job *actions_model.ActionRunJob) er
 		return fmt.Errorf("GetPushEventPayload: %w", err)
 	}
 
+	// Since the payload comes from json data, we should check if it's broken, or it will cause panic
+	switch {
+	case payload.Repo == nil:
+		return fmt.Errorf("repo is missing in event payload")
+	case payload.Pusher == nil:
+		return fmt.Errorf("pusher is missing in event payload")
+	case payload.HeadCommit == nil:
+		return fmt.Errorf("head commit is missing in event payload")
+	}
+
 	creator, err := user_model.GetUserByID(ctx, payload.Pusher.ID)
 	if err != nil {
 		return fmt.Errorf("GetUserByID: %w", err)