When deleting a collection delete its related data thoroughly

[arthurperton]

Fixes #3848 and #3890.

• Deletes entry localizations, if any
• Deletes the trees, if any

[jasonvarga]

I'd love if #3891 could be combined with this PR. As I mentioned there, it's such similar stuff happening right next to the other, I feel like it'd be better tested together.

You could rename the PR to something like "ensure related items are deleted when deleting a collection".

[arthurperton]

Yeah totally, I found the one issue while solving the other. The fixes are combined now into this PR.

[arthurperton]

@jasonvarga I wonder what you mean in this comment. What is it that needs doing?

[jasonvarga]

I think I just meant once it was merged.

[jasonvarga]

I get an error when I delete the collection when using multisite.

[2021-07-14 22:48:04] local.ERROR: Call to a member function pages() on null {"userId":"3ad6235d-8556-42dd-a500-9d7cc1373bd0","exception":"[object] (Error(code: 0): Call to a member function pages() on null at /users/jason/code/statamic/three/cms/src/Entries/Entry.php:167)
[stacktrace]
#0 /Users/jason/Code/statamic/three/sandbox/vendor/laravel/framework/src/Illuminate/Support/helpers.php(263): Statamic\\Entries\\Entry->Statamic\\Entries\\{closure}(Object(Statamic\\Structures\\CollectionTree))
#1 /users/jason/code/statamic/three/cms/src/Entries/Entry.php(171): tap(Object(Statamic\\Structures\\CollectionTree), Object(Closure))
#2 /Users/jason/Code/statamic/three/sandbox/vendor/laravel/framework/src/Illuminate/Support/helpers.php(263): Statamic\\Entries\\Entry->Statamic\\Entries\\{closure}(Object(Statamic\\Structures\\CollectionStructure))
#3 /users/jason/code/statamic/three/cms/src/Entries/Entry.php(172): tap(Object(Statamic\\Structures\\CollectionStructure), Object(Closure))
#4 /users/jason/code/statamic/three/cms/src/Entries/Collection.php(605): Statamic\\Entries\\Entry->delete()
#5 /Users/jason/Code/statamic/three/sandbox/vendor/laravel/framework/src/Illuminate/Collections/Traits/EnumeratesValues.php(235): Statamic\\Entries\\Collection->Statamic\\Entries\\{closure}(Object(Statamic\\Entries\\Entry), 2)
#6 /users/jason/code/statamic/three/cms/src/Entries/Collection.php(606): Illuminate\\Support\\Collection->each(Object(Closure))

[arthurperton]

Thanks I'll check that.

[arthurperton]

I get an error when I delete the collection when using multisite.

The last commit fixes the error. But when using multisite, the tree files are not deleted (well actually they are, but the get created again) and remain with { } inside. So this still needs some work.

[jasonvarga]

Closing as this has been sitting as a draft for a while. Feel free to reopen when it's ready or there's a better solution. Thanks!