Length check the ownerRepo array

src/github.com/matrix-org/go-neb/services/github/github.go

@@ -63,6 +63,12 @@ func (s *githubService) Plugin(roomID string) plugin.Plugin {
 						desc      *string
 					)
 					ownerRepo = args[0]
+					o := strings.Split(ownerRepo, "/")
+					if len(o) != 2 {
+						return &matrix.TextMessage{"m.notice",
+							`Usage: !github create owner/repo "issue title" "description"`}, nil
+					}
+
 					if len(args) == 2 {
 						title = &args[1]
 					} else if len(args) == 3 {
@@ -72,7 +78,6 @@ func (s *githubService) Plugin(roomID string) plugin.Plugin {
 						joinedTitle := strings.Join(args[1:], " ")
 						title = &joinedTitle
 					}
-					o := strings.Split(ownerRepo, "/")
 
 					issue, res, err := cli.Issues.Create(o[0], o[1], &github.IssueRequest{
 						Title: title,