Cannot Read Property 'toLowerCase' Of Undefined - REACT - FIRESTORE

I'm a bit new to React and Firestore and already trying to figure out what is happening for a couple of hours. I Try to make my filter function working with data which I receive fr

Solution 1:

Lint your App.css for any errors.

I encountered this message. I traced it to a CSS include:

.box-table { border-color:; border: 1px solid #dbdad8; }

The missing value of border-color: caused npm run build to fail.

Interestingly, the same file contained

.submenu-button.submenu-opened:after { background:; }

which caused no problems at all.