[MM-48409] lint and vet fix

api4/user.go

@@ -1962,7 +1962,7 @@ func loginCWS(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.App.AttachSessionCookies(c.AppContext, w, r)
 
 	redirectURL := *c.App.Config().ServiceSettings.SiteURL
-	if len(campaign) > 0 {
+	if campaign != "" {
 		if url, ok := campaignToURL[campaign]; ok {
 			redirectURL += url
 		}