Removing and adding a variable gives an error hard to understand
This is the case that generates the error:
- add a variable named
VAR1
, save - delete the variable, don't save
- add the variable again
- save
This happens because the saved list has a variable VAR1
that is also a "new" one.
We should at least give the name of the variable in the error message, otherwise the user must remove all the variables until the right one is found. A better solution is to automatically handle this case and update the variable instead of failing.