Can't use custom-webpack:dev-server with angular 9.1.0

[kamilchlebek]

Describe the Bug

• builder is set to @angular-builders/custom-webpack:dev-server

Running ng serve ends up with message:

ERROR in Cannot read property 'flags' of undefined

After debugging ng serve I can see it comes from method checkUnreachable inside typescript internals. It throws an exception while parsing node_modules/@angular-builders/custom-webpack/node_modules/typescript/lib/typescript.js

My guess it's because of @angular-devkit version mismatch after upgrading to 9.1.0.

• Deleting directory node_modules/@angular-builders/custom-webpack/node_modules/@angular-devkit fixes the issue - forces node to use @angular-devkit from node_modules

• Switching to default builder fixes the issue

Minimal Reproduction

https://github.com/kamilchlebek/angular-builders-issue-demo

Steps:

1. ng serve ➡️ error

Expected Behavior

ng serve finishes successfully.

Environment

Angular CLI: 9.1.0
Node: 10.16.0
OS: linux x64

Angular: 9.1.0
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.901.0
@angular-devkit/build-angular     0.901.0
@angular-devkit/build-optimizer   0.901.0
@angular-devkit/build-webpack     0.901.0
@angular-devkit/core              9.1.0
@angular-devkit/schematics        9.1.0
@ngtools/webpack                  9.1.0
@schematics/angular               9.1.0
@schematics/update                0.901.0
rxjs                              6.5.4
typescript                        3.8.3
webpack                           4.42.0
@angular-builders                 9.0.0

[just-jeb]

Yep, version mismatch is the root cause. Trying to find the best solution for this, thank you for such a well documented issue.

[just-jeb]

Should be fixed in v9.1.0-beta.1. Please update me if helped.

[faizplus]

Thanks @just-jeb for this quick fix. It is working with v9.1.0-beta.1

[kamilchlebek]

Thank you @just-jeb. It's good with v9.1.0-beta.1