Fix deployment to stopped Function Apps with clear error message

[Copilot]

When deploying to a stopped Function App, users were getting a confusing system error message instead of a clear indication of what was wrong:

Before:

Error: Serialization and deserialization of 'System.Reflection.MethodBase' instances is not supported

After:

Cannot deploy to function app "my-app" because it is currently stopped. Please start the function app before deploying.

Changes Made

• Added a state check in src/commands/deploy/deploy.ts that verifies the Function App is not in a STOPPED state before proceeding with deployment
• The check occurs early in the deployment process, right after site initialization, to fail fast with a helpful message
• Added proper error handling flags to suppress the misleading system error that was previously displayed
• Included appropriate telemetry tracking for stopped app deployment attempts

Implementation Details

The fix checks site.rawSite.state === 'STOPPED' and throws a localized error message. This approach:

• Only blocks deployments to explicitly stopped Function Apps
• Allows deployments to proceed for READY and UNKNOWN states (maintaining existing behavior)
• Provides clear, actionable guidance to users
• Follows the existing error handling patterns in the codebase

Testing

Added comprehensive unit tests covering all three possible site states (STOPPED, READY, UNKNOWN) to ensure the fix works correctly and doesn't break existing functionality.

Fixes #4662.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• aka.ms
  • Triggering command: gulp preTest (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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