Intercepting error of human detection pose not detected in hrnet.

[AlbertoCasasOrtiz]

This can be tested jut by selecting hrnet as pose detection algorithm, start a new session, and record neutral with no-one in camera range to be detected.

[antoinefalisse]

@AlbertoCasasOrtiz and @carmichaelong, very nice. A couple of questions:

1. Is the error message propagated to the frontend?
2. How about a use case where people use three cameras, but only two see the subject? I think we should not throw an error in that case, but rather attempt to process with the two cameras seeing the subject. This should be tested, but maybe instead of the error we could create an empty pickle file and catch a potential problem later in the code. Thoughts?

[AlbertoCasasOrtiz]

@antoinefalisse

1. Yes, it is propagated to the frontend. Before the fix, users would only see "2" as error message.

2. You are right. I am going to test the case for 2 phones (with one of them not detecting poses) and with 3 phones (with one and two of them not detecting poses).

[AlbertoCasasOrtiz]

Looks like its working for me, but I tried with three cameras occluding one of them and it does not work in that case. I then reseted to a previous commit and didn't work either.

I think someone else should take a second look just in case, I will revert in the meantime.

[antoinefalisse]

I think it is related to what I described above. It crashes (or throws an error with your update), when the camera does not see anything. If we were instead creating an empty file, we could deal with that. I can take a look, but busy with other things at the moment.