SassError: $map: null is not a map - Angular custom theme problem solving

Question

I created the following custom theme for my Angular project:

@use '@angular/material' as mat;
/* You can add global styles in this file or import other style files */


@include mat.core();

$f-brand: (
  50 : #e0f2f1,
  100 : #b3e0db,
  200 : #80cbc4,
  300 : #4db6ac,
  400 : #26a69a,
  500 : #009688,
  600 : #008e80,
  700 : #008375,
  800 : #00796b,
  900 : #006858,
  A100: #97ffec,
  A200: #64ffe3,
  A400: #31ffda,
  A700: #18ffd5,
  contrast: (
    50 : #000000,
    100 : #000000,
    200 : #000000,
    300 : #000000,
    400: #ffffff,
    500 : #ffffff,
    600 : #ffffff,
    700 : #ffffff,
    800 : #ffffff,
    900 : #ffffff,
    A100: #000000,
    A200: #000000,
    A400: #000000,
    A700: #000000,
  )
);

$primary: mat.define-palette($f-brand);

$theme: mat.define-light-theme($primary);

@include mat.all-component-themes($theme);

I also added the custom theme to my general styles.css file, but when I run "ng serve" I get the following error:

SassError: $map: null is not a map.
  ╷
9 │ $foreground-base: map.get($foreground, base);
  │ ^^^^^^^^^^^^^^^^^^^^^^^^^^
  ╵
  node_modules\@angular\material\core\ripple\_ripple-theme.scss 9:21 color()
  node_modules\@angular\material\core\ripple\_ripple-theme.scss 30:7 @content
  node_modules\@angular\material\core\theming\_theming.scss 376:3 private-check-duplicate-theme-styles()
  node_modules\@angular\material\core\ripple\_ripple-theme.scss 27:3 theme()
  node_modules\@angular\material\core\_core-theme.scss 48:5 @content
  node_modules\@angular\material\core\theming\_theming.scss 376:3 private-check-duplicate-theme-styles()
  node_modules\@angular\material\core\_core-theme.scss 47:3 theme()
  node_modules\@angular\material\core\theming\_all-theme.scss 43:5 @content
  node_modules\@angular\material\core\theming\_theming.scss 376:3 private-check-duplicate-theme-styles()
  node_modules\@angular\material\core\theming\_all-theme.scss 42:3 all-component-themes()
  src\styles-f-theme.scss 44:1 root stylesheet

By searching online, I found that "map.get" now seems to be "map-get". Unfortunately, I don't know how to fix this.

The Angular version used in my project is "14.0.5" and the Angular Material version is "14.0.4".

Answer 1

The reason why you get this error is because building a theme requires two color palettes: the main color and the accent color.

Add a new color palette or make your main color an accent color:

$theme: mat.define-light-theme($primary, $primary);