Add Additional Checkers to tell user not to call GDTask APIs under ed…

…itor.

GDTask/src/PlayerLoopRunner/GDTaskPlayerLoopRunner.cs

@@ -77,6 +77,7 @@ public static GDTaskPlayerLoopRunner Global
         {
             get
             {
+                RuntimeChecker.ThrowIfEditor();
                 if (s_Global != null) return s_Global;
 
                 var newInstance = new GDTaskPlayerLoopRunner();

GDTask/src/RuntimeGuard/RuntimeChecker.cs

@@ -0,0 +1,13 @@
+using System;
+using Godot;
+
+namespace GodotTask.Internal;
+
+internal static class RuntimeChecker
+{
+    internal static void ThrowIfEditor()
+    {
+        if(!Engine.IsEditorHint()) return;
+        throw new InvalidOperationException("Calling any GDTask API under editor is not supported.");
+    }
+}

GDTask/src/Triggers/AsyncTriggerExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using Godot;
+using GodotTask.Internal;
 
 namespace GodotTask.Triggers
 {
@@ -27,6 +28,7 @@ internal static T GetChild<T>(this Node node, bool includeRoot = true)
 
 		internal static T GetOrCreateChild<T>(this Node node) where T : Node, new()
 		{
+			RuntimeChecker.ThrowIfEditor();
 			T child = GetChild<T>(node);
 			if (child == null)
 				child = CreateChild<T>(node);