Better way to deal with an equilibrium having both an iota and current profile assigned to it

[dpanici]

Currently, when we have an equilibrium with both a current and iota profile assigned to it, we will throw an error when doing a default eq.solve for instance, because it will try to assign FixCurrent and FixIota as profile constraints.

However, one may still do things like eq.compute or even do an optimization with lsq-auglag (as that does not trigger an equilibrium solve). This leads to weird behavior where the equilibrium seems ok, but it is not using its assigned current profile at all and is instead using its iota profile (as we check for iota profile existing first in our compute functions for iota).

This is in some sense really just due to user error, they should know not to have both a current and iota profile attached, but when a user loads a wout file, by default the iota profile is used, and if they then assign a current profile to it without first setting eq.iota=None, then they may not realize they've made a mistake here. We could try to add a warning when a current/iota profileis assigned while the other profile attribute exists, and say UserWarning: Equilibrium already has existing current profile. Please remove with eq.current=None before using for optimization or equilibrium solving

Or, I would even be ok with automatically removing the other profile, as if I am assigning a current profile to an equilibrium, I almost certainly don't want the iota profile to still be attached to the equilibrium (and in most cases it will cause problems later). We could do this verbosely and still throw a warning saying UserWarning: Adding an iota profile to Equilibrium which already has existing current profile. Removing the Equilibrium current profile, as only one of iota/current is allowed to be assigned to an equilibrium.

I favor the latter option, but what do you guys think? @PlasmaControl/desc-dev

[YigitElma]

I think the second option is nicer. I like things to be automatic as long as it is verbose about it.

[Mandelbr0t]

I also favor the second option.