fix(v3): dirty union bug

[mmkal]

bug repro: https://stackblitz.com/edit/stackblitz-starters-swdj3e?file=index.test.js&startScript=test

Basically, zod v3 wrongly reports a "normal" error rather than a union error for a union of strict objects (and presumably other unions that set status=dirty:

import { test, expect } from 'vitest';
import { z } from 'zod';

test('hmm', () => {
  const union = z.union([
    z.object({ x: z.number() }).strict(),
    z.object({ y: z.number() }).strict(),
  ]);

  expect(union.safeParse({ x: 1, y: 1 })).toMatchInlineSnapshot(`
    {
      "error": [ZodError: [
      {
        "code": "unrecognized_keys",
        "keys": [
          "y"
        ],
        "path": [],
        "message": "Unrecognized key(s) in object: 'y'"
      }
    ]],
      "success": false,
    }
  `);
  expect(union.safeParse({ x: 1, y: 1 })).toMatchObject({
    success: false,
    error: {
      issues: [
        {
          code: 'invalid_union',
          unionErrors: [expect.any(z.ZodError), expect.any(z.ZodError)],
        },
      ],
    },
  });
});

Note: this does not repro in v4. I'm not sure if there's anything going into zod v3 still but opening this against main in hopes that it can get fixed in v3.

[netlify]

✅ Deploy Preview for guileless-rolypoly-866f8a ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	3b3af19
🔍 Latest deploy log	https://app.netlify.com/sites/guileless-rolypoly-866f8a/deploys/66ce259bc951de0008a45670
😎 Deploy Preview	https://deploy-preview-3727--guileless-rolypoly-866f8a.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.