Background color for separator line missing

[Tobboss]

Hi, I was struggling with my switch to Bubble Cards with the Bubble theme because my separator lines were invisible. I found out that when i add a

.bubble-line {
    background: var(--primary-text-color);
  }

as in the styling examples of the Bubble Card Github page, my line appeared.
I tracked it back by searching through the styles.ts of the separator which got it's color as

.bubble-line {
        border-radius: 6px;
        opacity: 0.5;
        flex-grow: 1;
        height: 6px;
        background-color: var(--bubble-line-background-color, var(--background-color, var(--secondary-background-color)));
        margin-right: 14px;
    }

I then looked up the theme if the --bubble-line-background-color is set somewhere, but I could not find it.
After manually adding this to the theme in the light and dark sections, it worked:

# Separator
      bubble-line-background-color: "var(--primary-text-color)"

So whether this should be added to the theme by default or I had another issue why there was no default value, where I could not yet find the reason.