handle empty data_point_out.json

[rajeee]

Pull Request Description

Sometimes, data_point_out.json can be present, but empty. This leads to obscure error downstream (see screenshot). This PR fixes the issue by treating empty json as not present.

Checklist

Not all may apply

• Code changes (must work)
• Tests exercising your feature/bug fix (check coverage report on Checks -> BuildStockBatch Tests -> Artifacts)
• Coverage has increased or at least not decreased. Update minimum_coverage in .github/workflows/coverage.yml as necessary.
• All other unit and integration tests passing
• Update validation for project config yaml file changes
• Update existing documentation
• Run a small batch run on Kestrel/Eagle to make sure it all works if you made changes that will affect Kestrel/Eagle
• Add to the changelog_dev.rst file and propose migration text in the pull request

[github-actions]

File	Coverage
All files	87%	✅
base.py	91%	✅
exc.py	57%	✅
hpc.py	78%	✅
local.py	70%	✅
postprocessing.py	84%	✅
utils.py	91%	✅
cloud/docker_base.py	92%	✅
sampler/base.py	79%	✅
sampler/downselect.py	33%	✅
sampler/precomputed.py	93%	✅
sampler/residential_quota.py	61%	✅
test/shared_testing_stuff.py	85%	✅
test/test_docker.py	33%	✅
test/test_local.py	97%	✅
test/test_validation.py	97%	✅
workflow_generator/base.py	90%	✅
workflow_generator/commercial.py	53%	✅
workflow_generator/residential_hpxml.py	86%	✅

Minimum allowed coverage is 33%

Generated by 🐒 cobertura-action against 8b4a68f

[nmerket]

I'm kind of curious what kind of file would run into this block. We're already handling the file being missing and it not being valid json, which is the error hit when the file is just empty. Based on messing around a little with it, I think the file would have to be just

null

I wonder where we're creating files like that?

[rajeee]

I ran into a case where it was just "{}" when ResStock fails in some specific step.