Robust CHID parsing

[chraibi]

This part

with open(smv_file_path, 'r') as infile:
    for line in infile:
        if line.strip() == "CHID":
            chid = infile.readline().strip()
            break

in simulation.py leads in my case to this error:

The failure happens because chid is never set while parsing the SMV (for some reason).

Maybe this function can be enhanced so that in this case the function returns an error.

A bit like:

CHID = None
# function above
if not chid:
    raise ValueError(f"Could not determine CHID from {smv_file_path}")

[lu-kas]

Adding a check for CHID makes sense. We will add it.

What worries me is that there is no CHID (or can not be found). Could you share the smv file? Or at least the first lines?

[chraibi]

The problem is not with fdsreader. In FDSvismap, fds-files are added with git lfs.

However, a misconfiguration in the CI, could not download the fds-file, so this error was triggered.

[JanVogelsang]

So we basically just need a "is the .smv file empty" check here. Further checking if the CHID is present would also be nice of course, but optional as every simulation should have a CHID.