Fix server NRE on clicking alerts with no OnClick (#2748)

* #2744 fix NRE on clicking alerts with no OnClick, and don't send the click
message unless the alert has an onclick

* #2744 fix NRE on clicking alerts with no OnClick, and don't send the click
message unless the alert has an onclick

Content.Client/GameObjects/Components/Mobs/ClientAlertsComponent.cs

@@ -222,6 +222,7 @@ namespace Content.Client.GameObjects.Components.Mobs
                 return;
             }
 
+            if (!alert.Alert.HasOnClick) return;
             SendNetworkMessage(new ClickAlertMessage(alert.Alert.AlertType));
         }
 

Content.Server/GameObjects/Components/Mobs/ServerAlertsComponent.cs

@@ -71,7 +71,7 @@ namespace Content.Server.GameObjects.Components.Mobs
                         break;
                     }
 
-                    if (AlertManager.TryGet(msg.AlertType, out var alert))
+                    if (AlertManager.TryGet(msg.AlertType, out var alert) && alert.OnClick != null)
                     {
                         alert.OnClick.AlertClicked(new ClickAlertEventArgs(player, alert));
                     }

Content.Shared/Alert/AlertPrototype.cs

@@ -72,8 +72,14 @@ namespace Content.Shared.Alert
         /// </summary>
         public bool SupportsSeverity => MaxSeverity != -1;
 
+        /// <summary>
+        /// Whether this alert is clickable. This is valid clientside.
+        /// </summary>
+        public bool HasOnClick { get; private set; }
+
         /// <summary>
         /// Defines what to do when the alert is clicked.
+        /// This will always be null on clientside.
         /// </summary>
         public IAlertClick OnClick { get; private set; }
 
@@ -102,6 +108,8 @@ namespace Content.Shared.Alert
             }
             AlertKey = new AlertKey(AlertType, Category);
 
+            HasOnClick = serializer.TryReadDataField("onClick", out string _);
+
             if (IoCManager.Resolve<IModuleManager>().IsClientModule) return;
             serializer.DataField(this, x => x.OnClick, "onClick", null);
         }