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Type error between Angular CLI and Browserslist when extending a browserslist config #30183

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@maharielrosario

Description

@maharielrosario

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build

Is this a regression?

  • Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

I have a fresh Angular 19 application and I am trying to extend a browserslist configuration from a TS library that I changed to JS while debugging this issue. When I run the Angular build, it throws a type error.

Originally, I opened a ticket with the browserslist team so you can see browserslist/browserslist#891 for further context. I was getting errors with browserslist as they are using CommonJS requires in their code and my library and app were ESM. After removing browserslist-useragent-regexp, simplifying my library to JS, and still getting errors, they asked me to reach out to Angular as they were thinking Angular had an over complicated environment.

Minimal Reproduction

Create a shareable config following browserslist's instructions here: https://github.com/browserslist/browserslist?tab=readme-ov-file#shareable-configs

Here is my particular example with text changed as it's for a client I'm working with:

Snippet of application's package.json:

 "type": "module", "browserslist": [ "extends @scope/browserslist-config-xxxx" ] 

Here is the library's code for this config:

index.js

constBROWSERSLIST_QUERY=['defaults'];exportdefaultBROWSERSLIST_QUERY;

snippet of package.json

 "type": "module", "browserslist": [ "extends @scope/browserslist-config-xxxx" ] 

Exception or Error

[error] TypeError: Cannot read properties of undefined (reading 'length') at find (/../node_modules/browserslist/parse.js:12:25) at matchBlock (/../node_modules/browserslist/parse.js:46:10) at /../node_modules/browserslist/parse.js:73:17 at Array.map (<anonymous>) at parse (/../node_modules/browserslist/parse.js:70:13) at parseQueries (/../node_modules/browserslist/index.js:454:16) at resolve (/../node_modules/browserslist/index.js:322:10) at Function.select (/../node_modules/browserslist/index.js:1163:14) at /../node_modules/browserslist/index.js:332:29 at Array.reduce (<anonymous>) 

Your Environment

Angular CLI: 19.2.8 Node: 22.14.0 Package Manager: npm 10.9.2 OS: darwin arm64 Angular: 19.2.7 ... common, compiler, compiler-cli, core, forms ... platform-browser, platform-browser-dynamic, router Package Version --------------------------------------------------------- @angular-devkit/architect 0.1902.8 @angular-devkit/build-angular 19.2.8 @angular-devkit/core 19.2.8 @angular-devkit/schematics 19.2.8 @angular/cli 19.2.8 @schematics/angular 19.2.8 rxjs 7.8.2 typescript 5.7.3 zone.js 0.15.0 

Anything else relevant?

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