[5.1] Add main region on error page

[Razzo1987]

Pull Request related to #42652 .
Read comment #42652 (comment)
Now whe are changing the semantic.

Summary of Changes

Add <main> on error.php template page.
Also when there is a module in the error-* position

Testing Instructions

Case 1: Go on page error and see the source
Case 2: Add module to error-403 or error-404 position. Go on page error and see the source

Actual result BEFORE applying this Pull Request

Case 1 and Case 2: There is no <main> element

Expected result AFTER applying this Pull Request

Case 1: Now the error message is inside the <main> element
Case 2: Now the module is inside the <main> element

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

Thanks to @brianteeman and @richard67 for the brainstorming ;)

[brianteeman]

You should also add the main region for the regular use

[richard67]

You should also add the main region for the regular use

@Razzo1987 Yes, Brian is right, it should also be added in the else branch like I wrote in my comment which you referred to:

I think the <main> should go to line 163 of the file changed by this PR, just after the <jdoc:include type="message" />, and it should be closed in line 177 (or 178 after adding the opening tag) just after the </blockquote> and before the </div>.

Here in 5.1-dev the line numbers stilll fit to my comment.

[Razzo1987]

Correct, thanks!

[richard67]

@Razzo1987 Now it needs to adapt the testing instructions so that both cases are checked, with and without any module on an error-403 or error-404 position.

[brianteeman]

I have tested this item ✅ successfully on c6d4534

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[viocassel]

I have tested this item ✅ successfully on c6d4534

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[Quy]

RTC

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[LadySolveig]

Thank you @Razzo1987 and also for testing to @brianteeman and @viocassel