Fix missing version in extensionBundle causing Python timer trigger runtime error

[Copilot]

Problem

When creating Python timer trigger projects, the generated host.json file contains an incomplete extensionBundle section with only the id property but missing the version property:

{
  "version": "2.0",
  "logging": { ... },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle"
    // Missing version property!
  }
}

This causes the Azure Functions runtime to fail during debugging with the error:

The value of version property in extensionBundle section of host.json file is invalid or missing. See https://aka.ms/functions-hostjson for more information

Root Cause

The issue was in src/utils/verifyExtensionBundle.ts line 47. The logic only checked if extensionBundle exists:

if (!hostJson.extensionBundle) {
    // Add complete bundle
} else {
    // Skip - BUG: this skips incomplete bundles too!
}

When an incomplete extensionBundle existed (with id but no version), the function would skip adding the missing version property, leaving the bundle in an invalid state.

Solution

Updated the condition to check for a complete extensionBundle with both id AND version:

if (!hostJson.extensionBundle || !hostJson.extensionBundle.id || !hostJson.extensionBundle.version) {
    // Add complete bundle (handles all incomplete cases)
} else {
    // Skip only when bundle is complete
}

Testing

• Added comprehensive tests covering all edge cases (missing bundle, missing version, missing id, empty bundle)
• Verified the fix resolves the exact scenario described in the issue
• Confirmed all project types benefit from more robust extensionBundle validation

Impact

• ✅ Python timer trigger projects now work without runtime errors
• ✅ All project types get more robust extensionBundle validation
• ✅ Edge cases (missing id, empty bundle) are properly handled
• ✅ Minimal change (1 line) with maximum impact

Fixes #4594.

Warning

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[manvkaur]

it should test against

[4.*, 5.0.0) as the default