Empty @switch block can't compile

[vlzware]

Which @angular/* package(s) are the source of the bug?

compiler-cli

Is this a regression?

Yes

Description

In the code I am working with, we have a section which looked like this:

<ng-container [ngSwitch]="type">
  <!-- commented out code -->
</ng-container>

This used to compile.

If I replace this with the new syntax like this:

@switch (type) {
  <!-- commented out code -->
}

it fails to compile with the error shown below.
The switch block contains commented out code for legacy reasons.

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

√ Browser application bundle generation complete.
<e> [webpack-dev-middleware] TypeError: Cannot read properties of undefined (reading 'index')
<e>     at TemplateDefinitionBuilder.visitSwitchBlock (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:28574:44)
<e>     at SwitchBlock.visit (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:3970:24)
<e>     at visitAll$1 (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:4184:34)
<e>     at TemplateDefinitionBuilder.visitElement (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:28324:9)
<e>     at Element$1.visit (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:3836:24)
<e>     at visitAll$1 (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:4184:34)
<e>     at TemplateDefinitionBuilder.buildTemplateFunction (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:27798:9)
<e>     at compileComponentFromMetadata (file:///C:/<myproject>/node_modules/@angular/compiler/fesm2022/compiler.mjs:30021:60)
<e>     at ComponentDecoratorHandler.compileFull (file:///C:/<myproject>/node_modules/@angular/compiler-cli/bundles/chunk-B5URQIVL.js:7010:17)
<e>     at TraitCompiler.compile (file:///C:/<myproject>/node_modules/@angular/compiler-cli/bundles/chunk-B5URQIVL.js:1688:38)

Please provide the environment you discovered this bug in (run ng version)

Angular CLI: 17.0.8
Node: 18.18.2
Package Manager: npm 10.2.5
OS: win32 x64

Angular: 17.0.8
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router, service-worker

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1700.8
@angular-devkit/build-angular   17.0.8
@angular-devkit/core            17.0.8
@angular-devkit/schematics      17.0.8
@angular/cdk                    17.0.4
@angular/material               17.0.4
@schematics/angular             17.0.8
rxjs                            7.8.1
typescript                      5.2.2
zone.js                         0.14.2

Anything else?

No response

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