代码：

@import '~@angular/material/theming';

@include mat-core();

$my-app-primary: mat-palette($mat-indigo);

$my-app-accent: mat-palette($mat-pink, A200, A100, A400);

$my-app-warn: mat-palette($mat-red);

$my-app-theme: mat-ligth-theme($my-app-primary, $my-app-accent, $my-app-warn);

@include angular-material-theme($my-app-theme);

错误提示：

ERROR in ./node_modules/raw-loader!./node_modules/postcss-loader/lib??embedded!./node_modules/sass-loader/lib/loader.js??ref--8-3!./src/styles.scss

Module build failed:

  $foreground: map_get($theme, foreground);

              ^

      Argument `$map` of `map-get($map, $key)` must be a map

      in /Volumes/work/imooc_angular4_taskmgr/taskmgr/node_modules/@angular/material/_theming.scss (line 1230, column 16)

webpack: Failed to compile.