Function Host starts despite bundle download failure

In certain scenarios, the Azure Function host continues to start even when the bundle download has failed. This leads to a critical issue where functions that rely on the bundle fail to index, resulting in a "binding not found" error. This behavior can cause silent failures in production environments.

Sample error log:
_The '{FunctionName}' function is in error: The binding type(s) 'cosmosDB' were not found in the configured extension bundle. Please ensure the type is correct and the correct version of extension bundle is configured._

Sample query
_FunctionsLogs
| where PreciseTimeStamp >= datetime(2025-08-11T21:55:16.8091712Z) and PreciseTimeStamp <= datetime(2025-08-11T21:55:56.7855533Z)
| where Tenant == "waws-prod-fra-005"
| where EventIpAddress == "10.20.32.109"
| where RoleInstance == "pd0MediumDedicatedWebWorkerRole_IN_32252"
| where Pid == 7096
| project PreciseTimeStamp, Level, Source, EventName, Summary, Details, ExceptionMessage, InnerExceptionMessage
| order by PreciseTimeStamp asc_

Investigative information

Repro steps
1. Deploy a function app that uses bindings from a bundle.
2. Simulate or observe a failure in the bundle download process.
3. Observe that the function host still starts.
4. Attempt to invoke a function that depends on the failed bundle.

Expected behavior
- The function host should not start when bundle download failure has occurred.

Actual behavior
- The function host starts even when the bundle download fails.
- Functions relying on the bundle fail to index with a "The binding type(s) not found" error. This will lead to those functions not running, and 404s being returned for http functions.

No source file or test is identified in the issue. Start by tracing the extension bundle download failure through host startup and reproduce the listed scenario; done means the host does not start after a bundle download failure, preventing bundle-dependent functions from indexing silently.

Written by the indexing model from the issue text.