Issue get external files dir

[Nishthajain7]

**

Purpose / Description

The app incorrectly showed a fatal error when initializeAnkiDroidDirectory() fails to create a new directory, even if a previously valid collection directory already exists. Add logic to check if an existing AnkiDroid directory is valid before showing the fatal error.

Fixes

• Fixes #19551

Approach

A fatal error is shown only if both:

• No existing valid directory is available, and
• Creating or accessing a new directory fails.

How Has This Been Tested?

• Ran unit tests in AnkiDroidAppTest.kt

Learning (optional, can help others)

Describe the research stage

• Executed libanki module tests

Checklist

Please, go through these checks before submitting the PR.

• [x] You have a descriptive commit message with a short title (first line, max 50 chars).
• [x] You have commented your code, particularly in hard-to-understand areas
• [x] You have performed a self-review of your own code
• [x] UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• [x] UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

The app incorrectly showed a fatal error when initializeAnkiDroidDirectory() fails to create a new directory, even if a previously valid collection directory already exists.

Could you submit an issue or walk me through the logic here?

[david-allison]

Ok, I'm at a computer, could you walk me through the logic. As I see it:

• A collection directory exists, but files cannot be written to it

• The fallback directory is unusable due to a fatal storage error

  • A user can neither write files to the current directory, nor restore to a valid directory
  • => Show a fatal error

• https://github.com/ankidroid/Anki-Android/commit/6c247c68dc69cee819894534d690d43a8456f34c

• https://github.com/ankidroid/Anki-Android/pull/19661

https://github.com/ankidroid/Anki-Android/blob/6c247c68dc69cee819894534d690d43a8456f34c/AnkiDroid/src/test/java/com/ichi2/anki/DeckPickerNoExternalFilesDirTest.kt#L66-L75

[Nishthajain7]

This issue is a different case:

• The existing collection directory is valid and writable.
• But getExternalFilesDir() returns null temporarily.
• The code treats this fallback failure as a fatal error without first checking the existing valid directory. So the app shows a fatal error even though it already has a usable path.

[david-allison]

• The existing collection directory is valid and writable. => getCurrentAnkiDroidDirectory returns a valid value
• The existing collection directory is valid and writable. => initializeAnkiDroidDirectory does not fail, and the method exits

https://github.com/ankidroid/Anki-Android/blob/6c247c68dc69cee819894534d690d43a8456f34c/AnkiDroid/src/main/java/com/ichi2/anki/AnkiDroidApp.kt#L279-L311

Given the above and this logic, I don't see how getExternalFilesDir would be called, the method should complete as expected