Warm start failing for domain without lakes if lake option is activated

[corentincarton]

I had a feedback from one of our users who was trying to run lisflood on a glofas subcatchment, which doesn't contain lakes, using our glofas settings template. For the first run, everything is fine but when doing a warm start, lisflood tries to find some lake files required for the initialisation but they are missing as we don't have lakes in that domain.
[Lakes]: setting LakeInitialLevelValue refers to a non existing path or a not well-formed float value
[Lakes]: setting LakePrevInflowValue refers to a non existing path or a not well-formed float value
[Lakes]: setting LakePrevOutflowValue refers to a non existing path or a not well-formed float value
But we don't actually need those files as we don't have lakes!

I'm wondering if we shouldn't deactivate the errors raised in the check_input_files function (in hydrological_modules/init.py) and just keep them as warning. If the input is not required, it will just raised a warning but will keep running. If the input is required, then it will fail in the module. This could help with debugging actually, as we'll see exactly which module is impacted by looking at the error stack.

@doc78, @ecCinziaMazzetti, @StefaniaGrimaldi, what do you think? Or is it too dangerous? Maybe I'm missing some loadmap default behaviour here...