Unclear message when Qupstream is NA

When we have NA in upstream discharge (observations), the error message is unclear.

For a run (I modified the following in the example InputsModel$Qupstream[5000] <- NA) :

OutputsModel <- RunModel_Lag(InputsModel = InputsModel,
+                              RunOptions = RunOptions, Param = Lag)
Error in if (any(OutputsModel$Qsim < 0)) { : 
  valeur manquante là où TRUE / FALSE est requis

For a calibration (according to @cyril.thebault):

Grid-Screening in progress(0%Error in FUN_MOD(InputsModel, RunOptions = RunOptions, Param = Param[iFirstParamRunOffModel:length(Param)]):
NA/NaN/Inf in foreign function call (arg2)

@olivier.delaigue and @david.dorchies, I think we need to better check NAs. In my opinion, NAs should be forbidden, such as are NAs for P and T.