CreateRunOptions and RunModel_GR5H* do not crash when Imax set to NULL

See

library(airGR)

## load of catchment data
data(L0123003)

## preparation of the InputsModel object
InputsModel <- CreateInputsModel(FUN_MOD = RunModel_GR5H, DatesR = BasinObs$DatesR,
                                 Precip = BasinObs$P, PotEvap = BasinObs$E)

## run period selection
Ind_Run <- seq(which(format(BasinObs$DatesR, format = "%Y-%m-%d %H:%M")=="2006-01-01 00:00"),
               which(format(BasinObs$DatesR, format = "%Y-%m-%d %H:%M")=="2006-12-31 23:00"))

## preparation of the RunOptions object
RunOptions <- CreateRunOptions(FUN_MOD = RunModel_GR5H, Imax = NULL,
                               InputsModel = InputsModel, IndPeriod_Run = Ind_Run)

It gives a warning for something else, but no error:

Warning message:
In CreateRunOptions(FUN_MOD = RunModel_GR5H, Imax = NULL, InputsModel = InputsModel,  :
  model warm up period not defined: default configuration used
  the year preceding the run period is used 

That is not desirable in my opinion (someone I know just made wrong simulations for this reason due to a bad reading of Imax values).