Simdexes created with a process should not raise exception when trying to access a variable that is not in the hdf5 file

[saroele]

It's because without process, ALL variables are saved in the hdf5 file.
The best solution is to try to open the original files again and extract the data from their. A warning seems appropriate to explain that this is not optimal, and that the values are NOT saved in the simdex.