gui: crash when leaving "Load from File" without file selection
Start the GUI, click "Load from File", click the close button => program crashes with message
HDF5-DIAG: Error detected in HDF5 (1.10.4) thread 140698351597440:
#000: ../../../src/H5F.c line 491 in H5Fopen(): invalid file name
major: Invalid arguments to routine
minor: Bad value
terminate called after throwing an instance of 'std::runtime_error'
what(): H5Fopen failed
Edited by Wuttke, Joachim