Enhance fetch_random_instance func

Handle cross-inst. redirect w/ broken health stats

Add check for instance version in cross-redirect

src/invidious/helpers/utils.cr

@@ -417,9 +417,31 @@ def fetch_random_instance
   filtered_instance_list = [] of String
   instance_list.as_a.each do |data|
     if data[1]["type"] == "https"
-      if data[1]["monitor"]
-        health = data[1]["monitor"].as_h["dailyRatios"][0].as_h["ratio"]
-        filtered_instance_list << data[0].as_s if health.to_s.to_f > 90
+      # Makes sure the instance isn't too outdated.
+      remote_version = data[1]["stats"]["software"]["version"]
+      remote_commit_date = remote_version.as_s.match(/\d{4}\.\d{2}\.\d{2}/)
+      next if !remote_commit_date
+      remote_commit_date = Time.parse(remote_commit_date[0], "%Y.%m.%d", Time::Location::UTC)
+      local_commit_date = Time.parse(CURRENT_VERSION, "%Y.%m.%d", Time::Location::UTC)
+
+      if (remote_commit_date - local_commit_date).abs.days <= 30
+        # as_nil? doesn't exist. Thus we'll have to handle the error rasied if
+        # as_nil fails.
+        begin
+          broken_health_monitoring = data[1]["monitor"].as_nil
+          broken_health_monitoring = true if broken_health_monitoring.nil?
+        rescue TypeCastError
+          broken_health_monitoring = false
+        end
+
+        if !broken_health_monitoring
+          health = data[1]["monitor"].as_h["dailyRatios"][0].as_h["ratio"]  
+          filtered_instance_list << data[0].as_s if health.to_s.to_f > 90
+        else
+          # We can't check the health if the monitoring is broken. Thus we'll just add it to the list
+          # and move on
+          filtered_instance_list << data[0].as_s
+        end
       end
     end
   end