--bs-nav-link-hover-color is not defined

[JohnRDOrazio]

I noticed that while hovering the Trashbin icon at the top right of the screen, it simply disappears. Checking the hover state in Chrome Dev Tools, I'm seeing this message:

--bs-nav-link-hover-color is not defined

webpack://./node_modules/bootstrap/scss/_nav.scss is referenced at line 33:

.nav-link:hover, .nav-link:focus {
    color: var(--bs-nav-link-hover-color);
}

Is this a bug or am I supposed to run something before doing a yarn start?