Better support of external state variables for MFront behaviours
This issue is meant to highlight a possible misuse of MFront behaviours.
If the behaviours declares an external state variable (corresponding to a "control variable" in
Code_Aster wording), its availability is not checked.
If not correctly declared, a nan value seems to be passed to the behaviour, which can be quite difficult to debug.
Note that the number of declared external state variables is not passed to the MFront behaviour, so even this basic check is not possible.
A few proposal can be made:
- Pass the number of declared external state variables
- Retrieve the list of external state variables from the MFront behaviour and make the appropriate check prior to the behavioiur integration (inside