Avoid null pointer exception when creating new stores

[JorgeMucientes]

Fixes crash: #10525

Description

Avoid null pointer exceptions during store creation when the Android system process death happens for the app.

Crash in action:

crash.mp4

Testing instructions

1. Trigger store creation flow from site picker.
2. Click on "Try for free"
3. Navigate to country picker step for example and send the app to the background
4. Run this from terminal adb shell am kill com.woocommerce.android.dev while the app is in background
5. Wait for about 5 seconds
6. Open the app and continue the store creation flow to the last step where the progress bar is shown. The app should not crash anymore after theme picker step (like in the screen recording above).

Fixed

fixCrash.mp4

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[wpmobilebot]

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

	App Name	WooCommerce Android
	Flavor	Jalapeno
	Build Type	Debug
	Commit	a388427
	Direct Download	woocommerce-prototype-build-pr10534-a388427.apk

[dangermattic]

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⚠️	PR is not assigned to a milestone.

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[JorgeMucientes]

The domain value is only for tracking purposes. So in the case of process death, it will be null and the !! will be causing the app to crash. Removed it. For the very few corner cases where storeData is null, we'll be tracking a null value, but is not a problem.

[JorgeMucientes]

In case the values from memory were whipped due to process death, we retrieve the required siteId for the new site from sharedPreferences.

[malinajirka]

Thanks for working on this @JorgeMucientes!

I've tested the app before the changes and after the changes and I can confirm it fixes the crash. However, it seems the solution ignores all the previous user choices. I tried selecting an industry and I killed the app. It seemed the store data were completely empty and my selection wasn't being taken into account. Wdyt?

[JorgeMucientes]

Hey @malinajirka. Thanks for the review!
Good point! Yes, that is true, in the unlikely case of app process death during store creation (which lasts around 1min so chances are really low) the user selected choices will be lost. Currently, we only save siteId and selectedTheme into disk because they are the only options that have an impact on the new store and thus are essential. The rest of the data is kept in memory because is "a nice to have" since its is merely used for tracking purposes.

However, I agree that we should probably save everything into DB and ensure all the data survives process death. But that would require several changes and I think is out of scope for this crash fix, so I've created a new issue to tackle that as a different task. Wdyt?

[malinajirka]

because they are the only options that have an impact on the new store and thus are essential. The rest of the data is kept in memory because is "a nice to have" since its is merely used for tracking purposes.

Ohh, interesting - I thought the choices are taken into consideration for customized content of the newly created site => that's how it works (or used to work at least) in the WordPress/Jetpack apps.

If that's truly the case and it doesn't have any impact on the UX, I agree this solution is good enough for this edge case. If it'd be affecting the final output, I'd personally prefer exiting the site creation flow and forcing users into starting over. Storing everything into the DB is definitely the best possible solution, but the required effort might not be worth it.

I'm approving the PR, feel free to merge it. Thanks!

[JorgeMucientes]

Just a couple clarifications @malinajirka

Ohh, interesting - I thought the choices are taken into consideration for customized content of the newly created site => that's how it works (or used to work at least) in the WordPress/Jetpack apps.

In the future afaik is meant to have an impact. For now, they are just options we sent to Tracks and to Woo backend for a better understanding of Woo Express customers.

I'd personally prefer exiting the site creation flow and forcing users into starting over.

Unfortunately, that is not an option or would be very complicated as it would require deleting the new site before the user start customising it. The moment the user clicks on "Try for free" in store creation first step, a new site is created immediately. So even if you abandon the process right away, the site is already created and will be present in the site picker the next time they open the app or the web.