fix vitest-environment-miniflare node 21 compatibility (#734)

Author: jkeys089

packages/shared/src/error.ts

@@ -15,8 +15,9 @@ export function prefixError(prefix: string, e: any): Error {
   if (e.stack) {
     return new Proxy(e, {
       get(target, propertyKey, receiver) {
-        const value = Reflect.get(target, propertyKey, receiver);
-        return propertyKey === "stack" ? `${prefix}: ${value}` : value;
+        return propertyKey === "stack"
+          ? `${prefix}: ${target.stack}`
+          : Reflect.get(target, propertyKey, receiver);
       },
     });
   }

packages/vitest-environment-miniflare/src/index.ts

@@ -99,6 +99,13 @@ export default <Environment>{
     delete mfGlobalScope.crypto;
     Object.defineProperty(global, "crypto", { get: () => crypto });
 
+    // `navigator` is defined as a getter on the global scope in Node 21+,
+    // so attempting to set it with `Object.assign()` would fail. Instead,
+    // override the getter with a new value.
+    const navigator = mfGlobalScope.navigator;
+    delete mfGlobalScope.navigator;
+    Object.defineProperty(global, "navigator", { get: () => navigator });
+
     // Attach all Miniflare  globals to `global`, recording originals to restore
     // in teardown
     const keys = Object.keys(mfGlobalScope);