feature: add traceback to service import error

[smidm]

Feature request

when bentoml serve <bento> --debug fails on bento import the error message is not helpful:

Error: [bentoml-cli] `serve` failed: Failed to load bento or import service ' <bento> '. 
If you are attempting to import bento in local store: `Failed to import module "pose": No module named 'pose'`, 
or if you are importing by python module path: 
`Failed to import module "service": libcudart.so.11.0: cannot open shared object file: No such file or directory`

It should show the ImportError traceback, at least in --debug mode.

I had to resort to:

cd ~/bentoml/bentos/pose/n7ptgfrkuontoatv/src/
python -c 'import service'

Motivation

easier debugging import errors while serving bentos

Other

No response

[ssheng]

@smidm Thanks for reporting this issue. We will look to address it in the next release.

[aarnphm]

@smidm Thanks for reporting once again, and this will be included in the next release.