The function Runtime is unable to start

I have a function app that will not run and immediately stops. I do not see any errors in the logs indicating why its stopping, or what is happening.

This application worked at one point when deployed to a different function app name. The only real difference should have been the addition to a function proxy, and deployment to a new function app name. However, we're also now doing a ZIP deploy kicked off from Azure DevOps instead of pulling the code from Azure Repos directly.

Error from the console:
```
Error:
The function runtime is unable to start.
Session Id: f6e6fe27e9734e1ca60776303504a573
Timestamp: 2019-01-14T16:30:41.921Z

```
- Function App version (1.0 or 2.0): ~2
- Region: South Central US

#### Repro steps

1. Start the function app.
2. Navigate to any function URL.

NOTE: You receive:
Function host is not running.

The report names no repository files, tests, or code entry points. Begin by reproducing the startup failure with the stated Function App version, proxy, and ZIP deployment details, then inspect the host startup diagnostics; done means the runtime starts and the function URL no longer reports that the host is not running.

Written by the indexing model from the issue text.