Improve no-debug option / Improve error messages

[frostedoyster]

I'm finding it very difficult to work without the --debug option. When that option isn't on, you can get very cryptic error messages that would be especially unhelpful for the users (and anyone trying to fix the issues). Take this as an example:

training_set:
  systems:
    read_from: qm9_reduced_100.xyz
    length_unit: angstrom
  targets:
    energy:
      key: hello
      unit: eV

where the "hello" key is not present in the .xyz file. This results in:

[2024-05-18 21:03:22][INFO] - This log is also available in 'outputs/2024-05-18/21-03-22/train.log'.
[2024-05-18 21:03:23][INFO] - random seed of this run is 193713243
[2024-05-18 21:03:23][INFO] - Setting up training set
ERROR: 'hello'

which completely hides the error message. Given that some training runs might be very expensive, I think it's a bad idea to have the user re-run it with --debug, especially because all issues with eval only show up at the end of training. I think the easiest solution would be to remove the flag

[ceriottm]

you can turn it around to have a --quiet option to turn off output and a --verbose when you want all details

[Luthaf]

On top of whatever changes we make to --debug, we should never produce an error message like ERROR: 'hello'. We can and should strive for more informative messages!

[PicoCentauri]

The only extra thing that --debug does is that the code will print the traceback to line where it broke

https://github.com/lab-cosmo/metatensor-models/blob/3fa7fbfe228bc1be06122c10201b984b3ded5edd/src/metatensor/models/__main__.py#L108-L112

And, --debug will print message in the loglevel DEBUG. Even though I think non of the models currently are using this possibility.

I think for a user this traceback is really useless. If a production software on your machine, like your vscode, produces an error there is no traceback to the typescript blob displayed. Probably just a more or less useful message. This is also what we should aim for.

Useful error message from a which a user knows what to do without reading the traceback call

100% agree with @Luthaf that the one you got is really bad.

Of course you find it annoying to add --debug but you are also a developer and not a user. Besides improving the error message you can always create an alias in your .bashrc.

alias metatens-models="metatensor-models --debug"