Which @angular/* package(s) are the source of the bug?
core
Is this a regression?
No
Description
When using resource.hasValue() in an if-statement, followed by an else-block, in that else-block, the variable resource will be considered never. This happens because of the type narrowing statement:
hasValue(): this is ResourceRef<Exclude<T, undefined>>
A resource()-call without defaultValue will return ResourceRef<T | undefined>, which gets "simplified" to ResourceRef<T>.
Since in non-strict mode Exclude<T, undefined> becomes T, suddenly the else-block gets treated as never, since it's the opposite of itself.
const res = resource({
request: () => ({}),
loader: async () => {
return "test";
},
});
if (res.hasValue()) {
} else {
res.status();
}Please provide a link to a minimal reproduction of the bug
No response
Please provide the exception or error you saw
X [ERROR] TS2339: Property 'status' does not exist on type 'never'. [plugin angular-compiler]
src/app/app.component.ts:57:10:
57 │ res.status();
╵ ~~~~~~~~
Please provide the environment you discovered this bug in (run ng version)
_ _ ____ _ ___
/ \ _ __ __ _ _ _| | __ _ _ __ / ___| | |_ _|
/ △ \ | '_ \ / _` | | | | |/ _` | '__| | | | | | |
/ ___ \| | | | (_| | |_| | | (_| | | | |___| |___ | |
/_/ \_\_| |_|\__, |\__,_|_|\__,_|_| \____|_____|___|
|___/
Angular CLI: 19.2.6
Node: 22.13.1
Package Manager: npm 9.6.4
OS: win32 x64
Angular: 19.2.5
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
Package Version
---------------------------------------------------------
@angular-devkit/architect 0.1902.6
@angular-devkit/build-angular 19.2.6
@angular-devkit/core 19.2.6
@angular-devkit/schematics 19.2.6
@angular/cdk 19.2.8
@angular/cli 19.2.6
@angular/material 19.2.8
@schematics/angular 19.2.6
rxjs 7.8.2
typescript 5.8.3
zone.js 0.15.0
Anything else?
I don't know how this could be addressed from a framework perspective, perhaps this is more of a TypeScript bug?
Which @angular/* package(s) are the source of the bug?
core
Is this a regression?
No
Description
When using
resource.hasValue()in an if-statement, followed by an else-block, in that else-block, the variableresourcewill be considerednever. This happens because of the type narrowing statement:hasValue(): this is ResourceRef<Exclude<T, undefined>>A
resource()-call withoutdefaultValuewill returnResourceRef<T | undefined>, which gets "simplified" toResourceRef<T>.Since in non-strict mode
Exclude<T, undefined>becomesT, suddenly the else-block gets treated asnever, since it's the opposite of itself.Please provide a link to a minimal reproduction of the bug
No response
Please provide the exception or error you saw
Please provide the environment you discovered this bug in (run
ng version)Anything else?
I don't know how this could be addressed from a framework perspective, perhaps this is more of a TypeScript bug?