Scheduler: cannot render schedule with direct meeting conflicts #282
Description
When it runs, the scheduler uses as starting point possible schedule information in the Meetings sheet. It essentially does not change the meetings that are already listed there. As a result, if one of the initial meetings conflicts with another (same slot and room assigned to two different groups), final schedule will also contain the problem.
The problem gets detected at validation phase, no problem there.
The problem is that the rendering code that produces the schedule grid sheet wasn't designed to handle such direct conflicts and typically fails in such cases with:
Exception: You must select all cells in a merged range to merge or unmerge them.
It may not make sense to generate a schedule sheet in such cases. Code should rather skip that and only create a "schedule issues" to report the problems.