fix amp validator message format

[ka2jun8]

Bug

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

fixes #31012

I referred to the previous code.

    if (errors == null) {
      if (Object.keys(amp).length > 0) {
        warnings = (warnings || []).concat(formatAmpMessages(amp) || [])
        if (!warnings.length) warnings = null
      }
    }

https://github.com/vercel/next.js/pull/29753/files

[timneutkens]

Can you add a test for this change?

[ka2jun8]

I think this is necessary because warnings come out from onStderr.

[timneutkens]

Thanks! great work on the tests 👍

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall decrease ✓

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
buildDuration	18s	18s	-16ms
buildDurationCached	3.3s	3.3s	-21ms
nodeModulesSize	346 MB	346 MB	-80 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.93	2.868	-0.06
/ avg req/sec	853.22	871.74	+18.52
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.328	1.353	⚠️ +0.02
/error-in-render avg req/sec	1882.77	1847.13	⚠️ -35.64

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.4 kB	28.4 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.45 kB	4.45 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.3 kB	13.3 kB	✓

Client Build Manifests

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall decrease ✓

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
buildDuration	19.4s	19.4s	-96ms
buildDurationCached	3.3s	3.3s	-2ms
nodeModulesSize	346 MB	346 MB	-80 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.946	2.909	-0.04
/ avg req/sec	848.71	859.47	+10.76
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.312	1.368	⚠️ +0.06
/error-in-render avg req/sec	1904.9	1827.98	⚠️ -76.92

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.5 kB	72.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.37 kB	2.37 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.47 kB	4.47 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.2 kB	13.2 kB	✓

Client Build Manifests

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	ka2jun8/next.js fix-amp-validator-message	Change
index.html gzip	532 B	532 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 512ad74