Fix potential bugs (#10513) (#10518)

* use e if it is an option
* potential nil so check err first
* check err first
* m == nil already checked

3 files changed, 7 insertions, 3 deletions

diff --git a/models/action.go b/models/action.go
index cd722cbe7c..161a7220c0 100644
--- a/models/action.go
+++ b/models/action.go
@@ -215,7 +215,7 @@ func (a *Action) getCommentLink(e Engine) string {
 		return "#"
 	}
 	if a.Comment == nil && a.CommentID != 0 {
-		a.Comment, _ = GetCommentByID(a.CommentID)
+		a.Comment, _ = getCommentByID(e, a.CommentID)
 	}
 	if a.Comment != nil {
 		return a.Comment.HTMLURL()
diff --git a/models/attachment.go b/models/attachment.go
index 81f2e15dad..7e59c7eef4 100644
--- a/models/attachment.go
+++ b/models/attachment.go
@@ -199,7 +199,7 @@ func GetAttachmentsByCommentID(commentID int64) ([]*Attachment, error) {
 
 func getAttachmentsByCommentID(e Engine, commentID int64) ([]*Attachment, error) {
 	attachments := make([]*Attachment, 0, 10)
-	return attachments, x.Where("comment_id=?", commentID).Find(&attachments)
+	return attachments, e.Where("comment_id=?", commentID).Find(&attachments)
 }
 
 // getAttachmentByReleaseIDFileName return a file based on the the following infos:
diff --git a/models/issue_comment.go b/models/issue_comment.go
index 3ba6790216..2494467bf2 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -749,8 +749,12 @@ func CreateRefComment(doer *User, repo *Repository, issue *Issue, content, commi
 
 // GetCommentByID returns the comment by given ID.
 func GetCommentByID(id int64) (*Comment, error) {
+	return getCommentByID(x, id)
+}
+
+func getCommentByID(e Engine, id int64) (*Comment, error) {
 	c := new(Comment)
-	has, err := x.ID(id).Get(c)
+	has, err := e.ID(id).Get(c)
 	if err != nil {
 		return nil, err
 	} else if !has {