Fix or understand grid requirements

• we are getting the exception

Exception: define_limit_grid could not detect combined datacard variables COMBCARDS,COMBCARDS_POINTS,COMBCARDS_VBF,COMBCARDS_VBF_POINTS

While only COMBCARDS is defined in setup

If that is commented we get the following

Exception: define_limit_grid encountered unstable limit interpolation with grid_min (-0.00987420952879) >= grid_max (-0.0618157023564)

Something should be added in this setup, or something should be ran before launching the grid?