Correctly Count Object References

[Timer]

Next.js would incorrectly error on a circular reference for the following:

const reused = {};
return {
  foo: reused,
  bar: reused
}

This pull request forks the reference count when traversing an object, and tells the user where the collision happened. Tests updated accordingly.

Error serializing `.k[3][1].nested[2]` returned from `test` in "/".
Reason: Circular references cannot be expressed in JSON (references: `.k`).

[ijjk]

Stats from current PR

Default Server Mode

General Overall increase ⚠️

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
buildDuration	8.3s	8s	-214ms
nodeModulesSize	56.5 MB	56.5 MB	⚠️ +390 B

Client Bundles (main, webpack, commons)

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
main-HASH.js gzip	5.76 kB	5.76 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..cfaa.js gzip	9.77 kB	9.77 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	55.4 kB	55.4 kB	✓

Client Bundles (main, webpack, commons) Modern

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
main-HASH.module.js gzip	4.77 kB	4.77 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.71 kB	6.71 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	51.4 kB	51.4 kB	✓

Legacy Client Bundles (polyfills)

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
polyfills-HASH.js gzip	18.9 kB	18.9 kB	✓
Overall change	18.9 kB	18.9 kB	✓

Client Pages

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_app.js gzip	1.09 kB	1.09 kB	✓
_error.js gzip	2.96 kB	2.96 kB	✓
hooks.js gzip	664 B	664 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	1.89 kB	1.89 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	7.38 kB	7.38 kB	✓

Client Pages Modern

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_app.module.js gzip	594 B	594 B	✓
_error.module.js gzip	2.06 kB	2.06 kB	✓
hooks.module.js gzip	370 B	370 B	✓
index.module.js gzip	212 B	212 B	✓
link.module.js gzip	1.48 kB	1.48 kB	✓
routerDirect..dule.js gzip	271 B	271 B	✓
withRouter.m..dule.js gzip	270 B	270 B	✓
Overall change	5.26 kB	5.26 kB	✓

Client Build Manifests

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_buildManifest.js gzip	61 B	61 B	✓
_buildManife..dule.js gzip	61 B	61 B	✓
Overall change	122 B	122 B	✓

Rendered Page Sizes

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
index.html gzip	916 B	916 B	✓
link.html gzip	925 B	925 B	✓
withRouter.html gzip	912 B	912 B	✓
Overall change	2.75 kB	2.75 kB	✓

---

Serverless Mode (Decrease detected ✓)

General Overall increase ⚠️

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
buildDuration	8.8s	8.5s	-379ms
nodeModulesSize	56.5 MB	56.5 MB	⚠️ +390 B

Client Bundles (main, webpack, commons)

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
main-HASH.js gzip	5.76 kB	5.76 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..cfaa.js gzip	9.77 kB	9.77 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	55.4 kB	55.4 kB	✓

Client Bundles (main, webpack, commons) Modern

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
main-HASH.module.js gzip	4.77 kB	4.77 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.71 kB	6.71 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	51.4 kB	51.4 kB	✓

Legacy Client Bundles (polyfills)

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
polyfills-HASH.js gzip	18.9 kB	18.9 kB	✓
Overall change	18.9 kB	18.9 kB	✓

Client Pages

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_app.js gzip	1.09 kB	1.09 kB	✓
_error.js gzip	2.96 kB	2.96 kB	✓
hooks.js gzip	664 B	664 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	1.89 kB	1.89 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	7.38 kB	7.38 kB	✓

Client Pages Modern

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_app.module.js gzip	594 B	594 B	✓
_error.module.js gzip	2.06 kB	2.06 kB	✓
hooks.module.js gzip	370 B	370 B	✓
index.module.js gzip	212 B	212 B	✓
link.module.js gzip	1.48 kB	1.48 kB	✓
routerDirect..dule.js gzip	271 B	271 B	✓
withRouter.m..dule.js gzip	270 B	270 B	✓
Overall change	5.26 kB	5.26 kB	✓

Client Build Manifests

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_buildManifest.js gzip	61 B	61 B	✓
_buildManife..dule.js gzip	61 B	61 B	✓
Overall change	122 B	122 B	✓

Serverless bundles Overall decrease ✓

	zeit/next.js canary	Timer/next.js fix-duplicate-refs	Change
_error.js gzip	293 kB	292 kB	-582 B
404.html gzip	1.32 kB	1.32 kB	✓
hooks.html gzip	956 B	956 B	✓
index.js gzip	293 kB	293 kB	-243 B
link.js gzip	301 kB	301 kB	-403 B
routerDirect.js gzip	299 kB	299 kB	⚠️ +155 B
withRouter.js gzip	299 kB	299 kB	⚠️ +169 B
Overall change	1.49 MB	1.49 MB	-904 B