Pull Request resolves #46338

• I read the [Generative AI policy](https://developer.joomla.org/generative-ai-policy.html) and my contribution is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

This PR fixes the conditional rendering of the update package message in the Upload & Update view.

Previously, the code accessed $this->updateInfo['object'] directly without verifying its existence, which could lead to undefined index notices and inconsistent message behavior.

Fix implemented:

• Added a safe isset() check before validating the object.
• Ensured that the update package message is displayed only when valid update data is available.
• The generic upload instruction message remains unaffected and is always displayed.

This change is minimal and limited strictly to the relevant conditional block without any refactoring.

Testing Instructions

1. Navigate to:

   Administrator → System → Joomla Update → Upload & Update
   

2. Perform the following tests:

Test Case 1: Update Available

• Ensure Joomla has an available update.

• Verify:

  • Generic message is displayed.
  • Update package message is displayed correctly below it.
  • No duplication or errors.

Test Case 2: No Update Available

• When no update is available:

• Verify:

  • Only the generic message is displayed.
  • Update package message is not shown.
  • No warnings or notices occur.

Hardcore Test Case: Missing / Invalid updateInfo['object']

• Temporarily simulate missing update object:

  unset($this->updateInfo['object']);

  OR:

  $this->updateInfo['object'] = null;

• Reload the Upload & Update page.

Verify:

• Generic message is displayed correctly.
• Update package message is NOT displayed.
• No PHP warnings, notices, or UI issues occur.
• System behaves safely even with incomplete update data.

Actual result BEFORE applying this Pull Request

• Direct access to $this->updateInfo['object'] could cause undefined index warnings.
• Update message rendering was not reliably guarded.
• Behavior could be inconsistent when update data was missing.

Expected result AFTER applying this Pull Request

• Update package message is displayed only when valid update data exists.
• Generic message is always displayed.
• No undefined index warnings.
• Stable and predictable UI behavior across all scenarios, including edge cases.

Proof (Video & Screenshots)

Before Fix (Video):

After Fix (Screenshot/Image):