Throw if ModuleActions is accessed to early.

+ some code comments.

Author: dimarobert

DNN Platform/DotNetNuke.Web.Mvc/AsyncMvcHostControl.cs

@@ -36,6 +36,7 @@ protected override void OnInitInternal(EventArgs e)
 
         protected override void OnPreRenderInternal(EventArgs e)
         {
+            // We need to defer execution to after the async task registered in OnInitInternal above, which will only get executed at the WebForms async point, just before PreRenderComplete.
             this.Page.RegisterAsyncTask(new PageAsyncTask(this.OnPreRenderAsync));
         }
 

DNN Platform/Library/UI/Containers/ActionBase.cs

@@ -113,6 +113,7 @@ protected void ProcessAction(string actionID)
         {
             if (this.ModuleControl is IAsyncModuleControl)
             {
+                // We need to defer accesing this.Actions as it could only be accesible after the WebForms async point.
                 this.Page.RegisterAsyncTask(new PageAsyncTask(ct => this.ProcessActionInternalAsync(actionID, ct)));
             }
             else

DNN Platform/Library/UI/Modules/ModuleInstanceContext.cs

@@ -511,13 +511,10 @@ private void LoadActions(HttpRequest request)
             if (actionable != null)
             {
                 // Async module controls populate ModuleActions only after their async task executes.
-                // Leave this.actions as null so the Actions getter retries once results are available.
                 if (this.moduleControl is IAsyncModuleControl && actionable.ModuleActions == null)
                 {
-                    this.actions = null;
-
-                    // TODO: Should we throw instead to be able to identify code that tries to call it too early?
-                    return;
+                    throw new InvalidOperationException("Too early to access the ModuleActions. For async controls, ModuleActions collection is available only after the framework executes the `Page.ExecuteRegisteredAsyncTasks()`. " +
+                        "More specifically, you have to either register an async task using `Page.RegisterAsyncTask()` or use any of the sync events starting from PreRenderComplete to access them.");
                 }
 
                 this.moduleSpecificActions = new ModuleAction(this.GetNextActionID(), Localization.GetString("ModuleSpecificActions.Action", Localization.GlobalResourceFile), string.Empty, string.Empty, string.Empty);

DNN Platform/Website/admin/Menus/ModuleActions/ModuleActions.ascx.cs

@@ -158,6 +158,7 @@ protected override void OnLoad(EventArgs e)
 
                 if (this.ModuleControl is IAsyncModuleControl)
                 {
+                    // We need to defer accesing this.Actions as it could only be accesible after the WebForms async point.
                     this.Page.RegisterAsyncTask(new PageAsyncTask(this.ProcessActionsAsync));
                 }
                 else