chore: clarify CLI network errors

[balazsorban44]

Makes it easier to detect why a network error occurred with the CLI or next info, based on #36344

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
buildDuration	18.7s	18.8s	⚠️ +89ms
buildDurationCached	7.3s	7.3s	⚠️ +6ms
nodeModulesSize	463 MB	463 MB	⚠️ +89 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.401	4.401	✓
/ avg req/sec	568	568.09	+0.09
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.702	1.714	⚠️ +0.01
/error-in-render avg req/sec	1468.97	1458.44	⚠️ -10.53

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.3 kB	72.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	193 B	193 B	✓
amp-HASH.js gzip	308 B	308 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	359 B	359 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.71 kB	5.71 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.64 kB	2.64 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	391 B	391 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.3 kB	16.3 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
index.html gzip	531 B	531 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
buildDuration	20.6s	21.1s	⚠️ +434ms
buildDurationCached	7.4s	7.4s	⚠️ +15ms
nodeModulesSize	463 MB	463 MB	⚠️ +89 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.6	4.536	-0.06
/ avg req/sec	543.52	551.2	+7.68
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.579	1.656	⚠️ +0.08
/error-in-render avg req/sec	1582.91	1509.27	⚠️ -73.64

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	29.1 kB	29.1 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.9 kB	72.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	324 B	324 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	357 B	357 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.76 kB	5.76 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.76 kB	2.76 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	392 B	392 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.5 kB	16.5 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js chore/show-fetch-error	Change
index.html gzip	529 B	529 B	✓
link.html gzip	543 B	543 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 812860e