Real-time planning with daemon solving: starting with an empty VRP must be allowed to return an empty valueRange

From dev list:

"I found that when start with and empty solution (0/0 customer/vehicles) the solver raise an << 'java.lang.IllegalStateException' exception. The @ValueRangeProvider annotated member (method getVehicleList on class xx.xxxx.xxxxx.domain.VehicleRoutingSolution) called on bean (TimeWindowedVehicleRoutingSolution-0925182702) must not return an empty valueRange ([]). If this a valid dataset, apply overconstrained planning as described in the documentation."

The unit test CloudBalancingDaemonTest doesn't see it because it doesn't start from an empty solution.

First we need a unit test, but the fix will go deep I fear: removing the fail fast is easy, but making sure it doesn't crash, NPE, uselessly loop once that fail fast is gone, that's another matter...