Question/Feature Request: How is a user notified of the reason for NONMEM run failure?

[billdenney]

There are many ways that NONMEM may fail to run via babelmixr2. Off the top of my head, some options are:

1. The runCommand is not given correctly (a babelmixr2 setup issue)
2. The runCommand is not valid for the system where it is used (an information technology support issue)
3. The NONMEM license file is not available or is expired
4. There is a control stream error (a babelmixr2 error in converting the model to NONMEM)
5. There is a dataset error (likely a babelmixr2 error in making the dataset NONMEM-ready; maybe a NONMEM error; ref NONMEM: Remove dose of zero #42)
6. NONMEM crashes in some way during estimation (a NONMEM error that we need to be able to tell the user about)
7. babelmixr2 (and therefore pmxTools under the surface) cannot read the NONMEM output.

There are probably more ways that I'm not thinking of.

It seems like there should be a way to tell the user when these things happen. I don't know that we have to cover all of these separately (for example, 1 and 2 are very similar and not likely to be distinguishable from the perspective of babelmixr2). But, we will get lots of questions or bug reports if we don't have clear errors pointing users to where the error is and a potential fix.

Currently, I don't think that we give clear error messages to the user about these things.