fix: when creating root, check if canvas is rendered into another window

src/core/createRoot.ts

@@ -5,6 +5,7 @@ import { ContextProvider } from '../components/Context.ts';
 import { isReadOnlyProperty } from '../helpers/isReadOnlyProperty.ts';
 import { log } from '../helpers/log.ts';
 import { prepareInstance } from '../helpers/prepareInstance.ts';
+import { getIsCanvasElement } from '../helpers/canvas.ts';
 import { reconciler } from './reconciler.ts';
 import { roots } from './roots.ts';
 
@@ -50,7 +51,7 @@ export function createRoot(
     {
         let canvas;
 
-        if (target instanceof HTMLCanvasElement)
+        if (getIsCanvasElement(target))
         {
             canvas = target;
         }

src/helpers/canvas.ts

@@ -0,0 +1,15 @@
+export function getIsCanvasElement(target: HTMLElement): target is HTMLCanvasElement {
+    if (target instanceof HTMLCanvasElement) return true;
+
+    /**
+     * In case Application is rendered into another window (created with window.open() and rendered into it using React portal)
+     * canvas is instance of openedWindow.HTMLCanvasElement, not global window.HTMLCanvasElement
+     * 
+     * Thus we need to check for that.
+     */
+    const OwnerWindowHTMLCanvasElement = target?.ownerDocument?.defaultView?.HTMLCanvasElement;
+
+    if (!OwnerWindowHTMLCanvasElement) return false;
+
+    return target instanceof OwnerWindowHTMLCanvasElement;
+}