Trying to use .HashSet from StackExchange.Redis for .NET and getting "Null value not valid in this context."

I have an api that returns values from the database to populate our footer dynamically. These footer values are stored as keys in Redis at the endpoint and then in the main application I'm getting the url of the current page and creating a Hash with the key being the current url and the 5 returned redis key/values from the api as HashEntries. I've shown the code below and right where the HashSet is (at the end) is where the error starts, but if I remove the cache.Hashset, the code runs fine. Do I need to prepopulate the hash or am I missing something obvious here?

//Get relative url after .com/
                var url = HttpContext.Current.Request.Url.ToString();
                var urlSplit = url.Split(new string[] { ".com/" }, StringSplitOptions.None);
                var finalUrl = urlSplit[1];

                //TODO: If url isn't in Redis, want to hit endpoint and load it into Redis
                //in the background with worker service/async call.
                var cache = RedisHelper.Connection.GetDatabase();
                var hashExists = cache.HashExists(finalUrl, "footer:recent-content");

                if (hashExists)
                {
                     recentContent = cache.HashGet(finalUrl, "footer:recent-content");
                     topPages = cache.HashGet(finalUrl, "footer:top-pages");
                     featuredContent = cache.HashGet(finalUrl, "footer:featured-content");
                     topIntegrations = cache.HashGet(finalUrl, "footer:top-integrations");
                     featuredIntegrations = cache.HashGet(finalUrl, "footer:featured-integrations");

                }
                else
                {
                    recentContent = cache.StringGet("footer:general:recent-content");
                    topPages = cache.StringGet("footer:general:top-pages");
                    featuredContent = cache.StringGet("footer:general:featured-content");
                    topIntegrations = cache.StringGet("footer:general:top-integrations");
                    featuredIntegrations = cache.StringGet("footer:general:featured-integrations");

                    HashEntry[] redisFooterHash = 
                        {
                        new HashEntry("footer:recent-content", recentContent),
                        new HashEntry("footer:top-pages", topPages),
                        new HashEntry("footer:featured-content", featuredContent),
                        new HashEntry("footer:top-integrations", topIntegrations),
                        new HashEntry("footer:featured-integrations", featuredIntegrations)
                        };

                    cache.HashSet(finalUrl, redisFooterHash);
                   }

Also, the reason the keys are footer:recent-content and footer:general... is that in the future we want each page to have a dynamic footer based on it's content.