Ivy and reflect-metadata causes TypeError

[noxi515]

🐞 bug report

Affected Package

not sure.

Is this a regression?

Yes. Angular8 and Angular9 (ivy disabled) works well.

Description

Using both @grapecity/wijmo.angular2.all library and import-metadata causes TypeError on bootstrap.

🔬 Minimal Reproduction

1. ng new to generate new project.
2. npm i -P @grapecity/wijmo.angular2.all to install library.
3. Add WjGridModule to AppModule, and edit app.component.html.
4. Add import 'reflect-metadata' in main.ts

https://github.com/noxi515/angular-wijmo-reflect-issue

🔥 Exception or Error

Reflect.js:541 Uncaught TypeError: decorator is not a function
    at DecorateConstructor (Reflect.js:541)
    at Object.decorate (Reflect.js:130)
    at push../node_modules/@grapecity/wijmo.angular2.grid/__ivy_ngcc__/index.js.__decorate (index.js:18)
    at index.js:45
    at Object../node_modules/@grapecity/wijmo.angular2.grid/__ivy_ngcc__/index.js (index.js:45)
    at __webpack_require__ (bootstrap:79)
    at Module../src/app/app.module.ts (app.module.ts:1)
    at __webpack_require__ (bootstrap:79)
    at Module../src/main.ts (main.ts:1)
    at __webpack_require__ (bootstrap:79)

🌍 Your Environment

Angular Version:

Angular CLI: 9.0.1
Node: 12.14.1
OS: win32 x64

Angular: 9.0.0
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.900.1
@angular-devkit/build-angular     0.900.1
@angular-devkit/build-optimizer   0.900.1
@angular-devkit/build-webpack     0.900.1
@angular-devkit/core              9.0.1
@angular-devkit/schematics        9.0.1
@angular/cli                      9.0.1
@ngtools/webpack                  9.0.1
@schematics/angular               9.0.1
@schematics/update                0.900.1
rxjs                              6.5.4
typescript                        3.7.5
webpack                           4.41.2

[filipesilva]

I think this happens because of processing done in Angular CLI, so I am transferring it there.

[petebacondarwin]

So the error is thrown because the decorators array is 1-based rather than 0-based. And we are iterating down to the zeroth term in the array.

See this screenshot...

[clydin]

This looks like it may be an issue with the reflect-metadata package. By including the package, the behavior of the TypeScript helper __decorate changes to use the Reflect.decorate function provided by reflect-metadata. As shown above, the Reflect.decorate function does not guard against undefined decorators. The __decorate helper, however, does provide a guard for such an occurrence when Reflect.decorate is not present (code).

Does the application or any of its dependencies directly use the reflect metadata functionality? Angular applications built with the CLI have not required a reflect metadata polyfill (core-js was used) since version 8.0.4. Before that version it was only required for JIT builds.

[dgp1130]

Also reflect-metadata is listed as deprecated: https://angular.io/guide/deprecations#reflect-metadata.

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