filterResourcesWithEvents removes the entire date column when it filters out a date's last resource (regression from #6149 fix, v7.1.0)

This report is about the feature added as a response to #6149

Reduced Test Case

https://codepen.io/arshaw/pen/MYpKqZZ?editors=0010

reusing the demo for the fix for #6149 here, toggle both filterResourcesWithEvents and datesAboveResources to simulate the bug described below.

Do you understand that if a reduced test case is not provided, we will intentionally delay triaging of your ticket?

• I understand

Which connector are you using (React/Angular/etc)?

React

Bug Description

With filterResourcesWithEvents and datesAboveResources in the demo above, Sep 10 has no events on any resource and loses its column and its date header entirely.

Expected: the date stays, rendered empty, with only the resource sub-columns filtered. #6149 asked to filter resources per day and never mentions removing dates.

This screenshot is taken on the "broken" view, with the requested correction drawn in with red (Sep 10 date lane is rendered, but empty, only resources with no events are filtered away):

Impact

The view silently changes size and ignores the desired date range. A week where only one day has resources renders as a one-day week, which reads as a broken date range rather than as filtering. N/A: The missing date also can't be clicked or drag-selected, so it can't be used to create anything on that day.