Hey,
I've been playing with EXOS and I noticed the following.
"configure vlan x delete port 2" does not throw an error when the port was not a member of the vlan in the first place.
Also, "configure vlan x add port 2" does not give a warning when the port was already a member before issuing the command
For the sake of transparency, I would find it useful if the switch gave some feedback in scenarios like these. Giving warnings in those cases can reduce the risk of administrative errors IMHO.