Do not launch share intent for a page that is null

[justtwago]

Fixes #19748

The problem seems to be occurred when the user tries to share a draft post that hasn't been saved to our local database - PageStore, so it returns null for the selected post id. I couldn't reproduce it, though.

To Test:

I haven't found a way to reproduce this bug since there should be a page on a drafts list that is not saved in the PostStore.
Please smoke test a page draft creation and generating a share link for the draft page.

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Regression Notes

1. Potential unintended areas of impact

   • Pages screen

2. What I did to test those areas of impact (or what existing automated tests I relied on)

   • Manual testing

3. What automated tests I added (or what prevented me from doing so)

   • N/A

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PR Submission Checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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UI Changes Testing Checklist:

• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• Talkback.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• Large and small screen sizes. (Tablet and smaller phones)
• Multi-tasking: Split screen and Pop-up view. (Android 10 or higher)

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr19749-0ad0d41
	Commit	0ad0d41
	Direct Download	wordpress-prototype-build-pr19749-0ad0d41.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr19749-0ad0d41
	Commit	0ad0d41
	Direct Download	jetpack-prototype-build-pr19749-0ad0d41.apk

Note: Google Login is not supported on these builds.

[antonis]

Thank you for picking this up @justtwago 🙇
The code change seems reasonable to me and I didn't notice any side effects in the app 🎉