InvalidCharacterError: Failed to execute 'add' on 'DOMTokenList' due to space in CSS variable token

[h1un]

When attempting to use element.classList.add() with a CSS custom property containing a space, the following error occurs:

Unhandled Runtime Error
InvalidCharacterError: Failed to execute 'add' on 'DOMTokenList': The token provided ('[--lexical-indent-base-value: 40px]') contains HTML space characters, which are not valid in tokens.

Possible Solutions:
element.classList.add('[--lexical-indent-base-value: 40px]');

->

1. Use style.setProperty instead:
   element.style.setProperty('--lexical-indent-base-value', '40px');
2. Remove the space from the token:
   element.classList.add('[--lexical-indent-base-value:40px]');