Added check for data being read from file, error message if it fails
Added check for data being read from file, error message if it fails

mne-tools/mne-cpp,LorenzE/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,LorenzE/mne-cpp,LorenzE/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,LorenzE/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp