Add missing typescript property to NextConfig

[Andarist]

This is similar to #27126 , #27446 and #27974

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

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
buildDuration	14.8s	14.7s	-50ms
buildDurationCached	3.4s	3.3s	-125ms
nodeModulesSize	61.7 MB	61.7 MB	⚠️ +375 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.611	2.652	⚠️ +0.04
/ avg req/sec	957.6	942.82	⚠️ -14.78
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.459	1.436	-0.02
/error-in-render avg req/sec	1713.61	1740.97	+27.36

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
745.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	23.3 kB	23.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	67.1 kB	67.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
_app-HASH.js gzip	979 B	979 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.67 kB	2.67 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	4.14 kB	4.14 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	318 B	318 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	13 kB	13 kB	✓

Client Build Manifests

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
_buildManifest.js gzip	491 B	491 B	✓
Overall change	491 B	491 B	✓

Rendered Page Sizes

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
index.html gzip	539 B	539 B	✓
link.html gzip	552 B	552 B	✓
withRouter.html gzip	534 B	534 B	✓
Overall change	1.63 kB	1.63 kB	✓

---

Webpack 4 Mode

General Overall increase ⚠️

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
buildDuration	12.2s	12.3s	⚠️ +31ms
buildDurationCached	5.1s	5.1s	-73ms
nodeModulesSize	61.7 MB	61.7 MB	⚠️ +375 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.652	2.719	⚠️ +0.07
/ avg req/sec	942.8	919.54	⚠️ -23.26
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.453	1.432	-0.02
/error-in-render avg req/sec	1720.85	1746.11	+25.26

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
16.HASH.js gzip	186 B	186 B	✓
677f882d2ed8..HASH.js gzip	14.1 kB	14.1 kB	✓
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	10.6 kB	10.6 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	68 kB	68 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
_app-HASH.js gzip	964 B	964 B	✓
_error-HASH.js gzip	3.8 kB	3.8 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.87 kB	2.87 kB	✓
head-HASH.js gzip	3.06 kB	3.06 kB	✓
hooks-HASH.js gzip	924 B	924 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	3 kB	3 kB	✓
withRouter-HASH.js gzip	295 B	295 B	✓
30809af5c834..565.css gzip	125 B	125 B	✓
Overall change	18.1 kB	18.1 kB	✓

Client Build Manifests

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
_buildManifest.js gzip	501 B	501 B	✓
Overall change	501 B	501 B	✓

Rendered Page Sizes

	vercel/next.js canary	Andarist/next.js add-typescript-config-to-next-config	Change
index.html gzip	586 B	586 B	✓
link.html gzip	597 B	597 B	✓
withRouter.html gzip	578 B	578 B	✓
Overall change	1.76 kB	1.76 kB	✓

Commit: 5fa83bd