Improve and refactor some types

[javivelasco]

While investigating #30833 I've noticed we are typing in router the PageLoader as any. In an attempt to fix that this PR refactors and simplify some types across the Router and the Pages Loader to leverage type inference more.

This also adds two TODO for two cases where the manifest can be set to empty which might be the cause of the mentioned issue. Nonetheless this can happen for pages as well and we must decide what to do about it (which can happen in a different PR) that is, falling back or failing right away.

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	javivelasco/next.js improve-types	Change
buildDuration	19.4s	19.1s	-294ms
buildDurationCached	3.6s	3.7s	⚠️ +11ms
nodeModulesSize	339 MB	339 MB	⚠️ +791 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js improve-types	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.047	3.016	-0.03
/ avg req/sec	820.4	829.03	+8.63
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.425	1.465	⚠️ +0.04
/error-in-render avg req/sec	1754.62	1707.02	⚠️ -47.6

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js improve-types	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	javivelasco/next.js improve-types	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js improve-types	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	javivelasco/next.js improve-types	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js improve-types	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

Diffs

Diff for main-HASH.js

@@ -1541,17 +1541,15 @@
           this.routeLoader = (0, _routeLoader).createRouteLoader(assetPrefix);
           this.buildId = buildId;
           this.assetPrefix = assetPrefix;
-          /** @type {Promise<Set<string>>} */ this.promisedSsgManifest = new Promise(
-            function(resolve) {
-              if (window.__SSG_MANIFEST) {
+          this.promisedSsgManifest = new Promise(function(resolve) {
+            if (window.__SSG_MANIFEST) {
+              resolve(window.__SSG_MANIFEST);
+            } else {
+              window.__SSG_MANIFEST_CB = function() {
                 resolve(window.__SSG_MANIFEST);
-              } else {
-                window.__SSG_MANIFEST_CB = function() {
-                  resolve(window.__SSG_MANIFEST);
-                };
-              }
+              };
             }
-          );
+          });
         }
         _createClass(PageLoader, [
           {
@@ -1626,8 +1624,8 @@
              * @param {string} route - the route (file-system path)
              */ key: "_isSsg",
             value: function _isSsg(route) {
-              return this.promisedSsgManifest.then(function(s) {
-                return s.has(route);
+              return this.promisedSsgManifest.then(function(manifest) {
+                return manifest.has(route);
               });
             }
           },

Diff for index.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

Diff for link.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

Diff for withRouter.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js improve-types	Change
buildDuration	20.1s	20.6s	⚠️ +431ms
buildDurationCached	3.7s	3.8s	⚠️ +95ms
nodeModulesSize	339 MB	339 MB	⚠️ +791 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js improve-types	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.023	3.107	⚠️ +0.08
/ avg req/sec	826.93	804.53	⚠️ -22.4
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.463	1.458	-0.01
/error-in-render avg req/sec	1708.52	1714.81	+6.29

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js improve-types	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	javivelasco/next.js improve-types	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js improve-types	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	2.38 kB	2.38 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	javivelasco/next.js improve-types	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js improve-types	Change
index.html gzip	533 B	533 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.61 kB	1.61 kB	✓

Diffs

Diff for main-HASH.js

@@ -1541,17 +1541,15 @@
           this.routeLoader = (0, _routeLoader).createRouteLoader(assetPrefix);
           this.buildId = buildId;
           this.assetPrefix = assetPrefix;
-          /** @type {Promise<Set<string>>} */ this.promisedSsgManifest = new Promise(
-            function(resolve) {
-              if (window.__SSG_MANIFEST) {
+          this.promisedSsgManifest = new Promise(function(resolve) {
+            if (window.__SSG_MANIFEST) {
+              resolve(window.__SSG_MANIFEST);
+            } else {
+              window.__SSG_MANIFEST_CB = function() {
                 resolve(window.__SSG_MANIFEST);
-              } else {
-                window.__SSG_MANIFEST_CB = function() {
-                  resolve(window.__SSG_MANIFEST);
-                };
-              }
+              };
             }
-          );
+          });
         }
         _createClass(PageLoader, [
           {
@@ -1626,8 +1624,8 @@
              * @param {string} route - the route (file-system path)
              */ key: "_isSsg",
             value: function _isSsg(route) {
-              return this.promisedSsgManifest.then(function(s) {
-                return s.has(route);
+              return this.promisedSsgManifest.then(function(manifest) {
+                return manifest.has(route);
               });
             }
           },

Diff for index.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

Diff for link.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

Diff for withRouter.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-e3abba72f33d04ea.js"
+      src="/_next/static/chunks/main-1841f7ac14edab09.js"
       defer=""
     ></script>
     <script

Commit: 6d3c00a

[timneutkens]

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