Removing unit which cannot be removed shows no error

[mdavis-xyz]

Steps to reproduce

1. Add a model such that one unit is the subordinate of another (e.g. ntp and ubuntu)
2. Try to remove that subordinate unit with a command juju remove-unit ntp/0.
3. It says: removing unit ntp/3 failed: unit "ntp/3" is a subordinate
4. Try to remove that unit in the GUI

Expected behavior

The webui should throw an error message saying that the unit cannot be removed because it is a subordinate.
This should appear when you click commit (or before)

Actual behavior

Nothing happens. The flow is the same as a successful removal.
Nothing is shown to the user to make them suspect that the removal was not successful, other than the fact that the unit is still there.

[hatched]

Dev investigation needed

This notification used to exists, did it get removed or is it just broken?

[clagom]

@hatched did we discover if it was removed or broken?

[hatched]

Nope