Fixed "if newsletter module disabled, customer backend would blank without notice"

[sidealice]

removeable for the wishlist/giftmessage/sendtofriend/newsletter modules

[addison74]

This PR does not have a proper description. It would be natural to understand the issue, how to reproduce it and how to fix it. Looking in the source code and understanding the changes is not a thing at all a professional approach.

[kiatng]

I cannot replicate this issue:

1. I disable Mage_Newsletter in the Advanced tab in backend System Configuration.
2. I disable the cache for Configurations, Layouts, and Blocks.
3. I navigate to a backend customer page.
4. I can see the tab Newsletter, on the page it's a grid. I do not see a blank page.

Question: did you remove the Newsletter code from the core?

[kiatng]

A suggestion on PR: limit the file changes to one issue to make it easier to review. You have changes to files that do not seem to relate to Newsletter. Can you please remove those changes and commit again? You can make separate PRs for those which are removed.

[sidealice]

I cannot replicate this issue:

1. I disable Mage_Newsletter in the Advanced tab in backend System Configuration.
2. I disable the cache for Configurations, Layouts, and Blocks.
3. I navigate to a backend customer page.
4. I can see the tab Newsletter, on the page it's a grid. I do not see a blank page.

Question: did you remove the Newsletter code from the core?

Yes, if disabled the module or remove the code you can see the problem.
And this would help to sepreate the modules out of core. In the future OM can maintain necessary core, the other modules e.g. newsletter/wishlist/giftmessage/sendtofriend could be a module better.

[sidealice]

This PR does not have a proper description. It would be natural to understand the issue, how to reproduce it and how to fix it. Looking in the source code and understanding the changes is not a thing at all a professional approach.

Yes, I may update the description to ' support remove the wishlist/giftmessage/sendtofriend/newsletter module without issues'

[kiatng]

As suggested by @elidrissidev, we need to do a proper separation of concerns. Mage_Customer depends on the following modules:

magento-lts/app/etc/modules/Mage_Customer.xml

Lines 28 to 32 in 5318b86

	<depends>
	<Mage_Dataflow/>
	<Mage_Directory/>
	<Mage_Eav/>
	</depends>

All other modules here should be separated:

1. Mage_Sales
2. Mage_Catalog
3. Mage_Newsletter
4. Mage_Wishlist

Besides the tabs, which can be easily added with the event adminhtml_block_widget_tabs_html_before (see PR #1358), the rendering of the pages need to be separated as well:

Related to PR #2455. It means also PR #2533. And down the rabbit hole. What should we do?

[elidrissidev]

After looking more into this, IMO it's better to keep the refactoring until another major version, since it means moving classes around which breaks BC. For now, handling with a condition is good enough.

[fballiano]

I'll try to rebase in order to get this approved

[fballiano]

this time it worked correctly, so I'm ok with this PR