Angular 8 无法读取未定义的属性“地图”

Question

I am using Angular 8 for a project and after I installed @angular/material I tried to serve the application and I got this error. Never happened before, I get no stack at all.. that's it. Does anyone know something? Searching on the internet I found nothing.

I added lines to the code below so I can refer to:

• line 13 is the error
• line 3 I read something strange, what does that mean? Angular compiler specifies to compile es2015..

Thanks

1 ng serve
2 0% compiling
3 Compiling @angular/core : es2015 as esm2015
4 10% building 3/3 modules 0 activei ｢wds｣: Project is running at http://localhost:4200/webpack-dev-server/
5 i ｢wds｣: webpack output is served from /
6 i ｢wds｣: 404s will fallback to //index.html

7 chunk {main} main.js, main.js.map (main) 2.02 kB [initial] [rendered]
8 chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 127 kB [initial] [rendered]
9 chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]
10 chunk {styles} styles.js, styles.js.map (styles) 1.29 MB [initial] [rendered]
11 chunk {vendor} vendor.js, vendor.js.map (vendor) 340 kB [initial] [rendered]
12 Date: 2020-05-14T10:52:07.242Z - Hash: f6d075528a2e8bb42b38 - Time: 3912ms

13 ERROR in Cannot read property 'map' of undefined
14 ** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **
15 i ｢wdm｣: Failed to compile.

Answer 1

Before ng serve , execute npm install

This will brings all the node modules to your project through CLI..

Answer 2

I solved the issue by downgrading the @angular/core module to 9.15!