Fix UI crash when user navigates away before the download dialog appears

[elvakang]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

• Fixed a UI crash that occurs when a user navigates away before the download dialog appears.
• The crash was caused by an IllegalStateException when showing DownloadDialog after the fragment's state was saved.
• Implemented checks to ensure the fragment is added and its state is not saved before displaying the dialog, preventing unsafe transactions and avoiding crashes.

Before/After Screenshots/Screen Record

• Before:

Screen_recording_20241019_234611.mp4

• After:

Screen_recording_20241020_000319.mp4

Fixes the following issue(s)

• Fixes UI Crash When Navigating to Channel from Download Prompt #11468

APK testing

The APK can be found by going to the "Checks" tab below the title. On the left pane, click on "CI", scroll down to "artifacts" and click "app" to download the zip file which contains the debug APK of this PR. You can find more info and a video demonstration on this wiki page.

Due diligence

• I read the contribution guidelines.

[TobiGr]

Thank you. No crash is better than a crash. The solution is not perfect because the dialog is just not shown. But I am ok with that. We should however document this problem. Please add a comment explaining why the check is performed as it is and rebase your PR

[elvakang]

Thank you. No crash is better than a crash. The solution is not perfect because the dialog is just not shown. But I am ok with that. We should however document this problem. Please add a comment explaining why the check is performed as it is and rebase your PR

I've added the comment explaining the checks in code and rebased the branch. Let me know if there's anything else needed.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[TobiGr]

Leaving this open for a second review.

Please let me know if you are an ANU student for internal statistics and because I am writing my master thesis about open source contributions as part of learning computer science and computer science education at university.

[elvakang]

Leaving this open for a second review.

Please let me know if you are an ANU student for internal statistics and because I am writing my master thesis about open source contributions as part of learning computer science and computer science education at university.

Yes, I am an ANU student, and this PR is part of my coursework on open source contributions.