`getManagerProjectsModelArray` mapped every project manager to its project
without checking that the project is in the store, so one row pointing at a
deleted project produced a null the caller then read `id` off — taking down
the whole home view. `getMembershipProjectsModelArray` had the same hole one
level up, destructuring `board.project` before testing `board`.
The projects endpoint fed exactly that state: it derived the id list for the
included records from the manager rows, so a `project_manager` row whose
project no longer exists shipped a manager for a project missing from `items`.
Board memberships had the same gap. Both id lists now come from the records
that actually exist.
Daniel Hiller