chore: add performance polyfills and dispose crash harness test

Add performance.measure/console.timeStamp polyfills to match Expo
environment. Add harness test for rapid file switching. The crash
only reproduces on React 19 (RN 0.83+) where logComponentRender
deep-diffs props, but the test validates the pattern doesn't crash
on RN 0.79.

Also includes the callDispose fix from #227.

Author: mfazekas

example/__tests__/dispose-prop-diffing.harness.tsx

@@ -55,15 +55,16 @@ describe('dispose during Fabric prop diffing', () => {
     // Wait for initial file to load
     await new Promise((r) => setTimeout(r, 500));
 
-    // Rapid 3x switch — same pattern that crashes on RN 0.83
+    // Rapid 3x switch — same pattern that crashes when React's
+    // logComponentRender diffs old vs new props on the disposed object
     setIdx!((i) => i + 1);
-    await new Promise((r) => setTimeout(r, 50));
+    await new Promise((r) => setTimeout(r, 500));
     setIdx!((i) => i + 1);
-    await new Promise((r) => setTimeout(r, 50));
+    await new Promise((r) => setTimeout(r, 500));
     setIdx!((i) => i + 1);
 
     // Wait for everything to settle
-    await new Promise((r) => setTimeout(r, 500));
+    await new Promise((r) => setTimeout(r, 1000));
 
     // If we get here without crashing, the test passes
     expect(true).toBe(true);
@@ -85,10 +86,10 @@ describe('dispose during Fabric prop diffing', () => {
 
     for (let i = 0; i < 10; i++) {
       setIdx!((j) => j + 1);
-      await new Promise((r) => setTimeout(r, 30));
+      await new Promise((r) => setTimeout(r, 200));
     }
 
-    await new Promise((r) => setTimeout(r, 500));
+    await new Promise((r) => setTimeout(r, 1000));
     expect(true).toBe(true);
 
     cleanup();

example/src/polyfills.js

@@ -1,4 +1,17 @@
 /* global globalThis */
+// Polyfill performance.measure and console.timeStamp BEFORE React loads
+// to enable supportsUserTiming in ReactFabric-dev.js (same as Expo environment).
+// Without this, the dispose-during-prop-diffing crash only reproduces on Expo.
+if (typeof console.timeStamp !== 'function') {
+  console.timeStamp = () => {};
+}
+if (
+  typeof performance !== 'undefined' &&
+  typeof performance.measure !== 'function'
+) {
+  performance.measure = () => {};
+}
+
 // Polyfill EventTarget and Event for chai 6.x (used by react-native-harness).
 // Hermes on RN 0.79 doesn't have these Web APIs.
 // Must load before any react-native-harness import.

src/core/callDispose.ts

@@ -4,8 +4,45 @@ interface Disposable {
   dispose(): void;
 }
 
-/** Safely calls dispose(), ignoring errors from https://github.com/mrousavy/nitro/issues/1083 */
+/**
+ * Safely disposes a Nitro HybridObject.
+ *
+ * Before calling dispose(), overrides all JS-visible properties with undefined
+ * so that React Fabric can safely diff old props without crashing. Without this,
+ * Fabric's cloneNodeWithNewProps reads properties (e.g. toString, artboardNames)
+ * from the disposed object whose NativeState is already null, causing:
+ *   "Cannot get hybrid property ... - `this`'s `NativeState` is `null`"
+ *
+ * Also handles https://github.com/mrousavy/nitro/issues/1083
+ */
 export function callDispose(obj: Disposable): void {
+  // Override inherited (prototype) properties — these are the Nitro HybridObject
+  // getters that would throw after dispose. Own properties are left alone since
+  // they are plain JS values, not native getters.
+  for (const key in obj) {
+    if (Object.prototype.hasOwnProperty.call(obj, key)) continue;
+    if (key === '__type' || key === 'dispose') continue;
+    try {
+      Object.defineProperty(obj, key, {
+        value: undefined,
+        enumerable: false,
+        configurable: true,
+      });
+    } catch (_) {
+      // non-configurable — skip
+    }
+  }
+
+  try {
+    Object.defineProperty(obj, 'toString', {
+      value: () => '[disposed HybridObject]',
+      enumerable: false,
+      configurable: true,
+    });
+  } catch (_) {
+    // skip
+  }
+
   try {
     obj.dispose();
   } catch (error) {