Empty simulation output for failed runs in v0.18

[aspeake]

Describe the bug
When running with bsb v0.18 on Eagle, my simulations_job*.tar.gz directories are empty when all simulations fail. The job.out files indicate that the jobs were run successfully, and when running with bsb v0.17.1 I can see in the singularity_output.log files that the source of the error is an OS-bstock issue, and therefore some simulation output files should still exist.

To Reproduce
The yml and buildstock files used are attached in this thread: https://openstudioteam.slack.com/archives/C4FCA4KNW/p1590504982005300

Running these on the singleunit branch should cause all simulations to error out, and I expect the simulation output directories to be empty.

Platform (please complete the following information):

• Simulation platform: Eagle
• BuildStockBatch version, branch, or sha: v0.18
• OpenStudio-BuildStock version, branch, or sha: OS branch singleunit

[nmerket]

Thanks for submitting the bug report. I'm not exactly sure what's going on here, but would you @aspeake and @rajeee like to "sit down" with me while I debug this? I'd like to show someone how to set up debugging on Eagle.

[nmerket]

After a really fun remote debugging session, we found two issues:

1. n_buildings_represented wasn't in the yml file and for some reason isn't required in the schema. It should be required in the schema. Any objections to that @rHorsey?
2. This code meant to catch and report any unexpected errors in the simulation is silently letting errors by when we hit a KeyError here.

@rajeee has volunteered as tribute to work on at least number 2 above.

[nmerket]

Part 1 is handled in #177.

[nmerket]

@rajeee Any chance you could find some time to work on this?