refactor(runtime): seal ES module namespace object instead of feezing (#15914)

Author: sheremet-va

packages/vite/src/node/ssr/runtime/__tests__/server-runtime.spec.ts

@@ -87,11 +87,22 @@ describe('vite-runtime initialization', async () => {
 
   it('exports is not modifiable', async ({ runtime }) => {
     const mod = await runtime.executeUrl('/fixtures/simple.js')
+    expect(Object.isSealed(mod)).toBe(true)
     expect(() => {
       mod.test = 'I am modified'
     }).toThrowErrorMatchingInlineSnapshot(
       `[TypeError: Cannot set property test of [object Module] which has only a getter]`,
     )
+    expect(() => {
+      delete mod.test
+    }).toThrowErrorMatchingInlineSnapshot(
+      `[TypeError: Cannot delete property 'test' of [object Module]]`,
+    )
+    expect(() => {
+      Object.defineProperty(mod, 'test', { value: 'I am modified' })
+    }).toThrowErrorMatchingInlineSnapshot(
+      `[TypeError: Cannot redefine property: test]`,
+    )
     expect(() => {
       mod.other = 'I am added'
     }).toThrowErrorMatchingInlineSnapshot(

packages/vite/src/node/ssr/runtime/esmRunner.ts

@@ -34,7 +34,7 @@ export class ESModulesRunner implements ViteModuleRunner {
       context[ssrExportAllKey],
     )
 
-    Object.freeze(context[ssrModuleExportsKey])
+    Object.seal(context[ssrModuleExportsKey])
   }
 
   runExternalModule(filepath: string): Promise<any> {