If the SlotManager receives a slot report from an unknown task manager it logs 2 messages:
This leads to misleading output since it appears like the slot manager received 2 separate slot reports, with the first being for a known instance, the latter for an unknown one. This cost some time as I couldn't figure out why the "latter" report was suddenly being rejected.
I propose moving the first debug message into the non-null branch.
Till Rohrmann WDYT?