Import/export does not handle named arrays

[igorschoester]

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• I've searched for any related issues and avoided creating a duplicate issue.

Please give us a description of what happened

To Reproduce

Step-by-step reproduction instructions

1. Enable the Wincher integration feature
2. Connect with Wincher
3. Export settings
4. Search for wincher_tokens and notice missing keys, i.e. 6 times wincher_tokens[] = ""
5. Copy the export and paste in the import settings
6. Import the settings
7. Edit a post
8. You will now get PHP notices about missing key names

Expected results

1. Exporting and then importing should not result in differences

Actual results

1. Resulting in differences

Screenshots, screen recording, code snippet

If possible, please provide a screenshot, a screen recording or a code snippet which demonstrates the bug.

Technical info

It seems we never supported named arrays:

wordpress-seo/admin/class-export.php

Lines 139 to 142 in 53bc874

	for ( $i = 0; $i < $count; $i++ ) {
	$elem_check = ( $elem[ $i ] ?? null );
	$this->write_setting( $key . '[]', $elem_check );
	}

But we do use those. Not just for Wincher.

• If relevant, which editor is affected (or editors):

• Block Editor
• Gutenberg Editor
• Elementor Editor
• Classic Editor
• Other:

• Which browser is affected (or browsers):

• Chrome
• Firefox
• Safari
• Other:

Used versions

• Device you are using:
• Operating system:
• PHP version:
• WordPress version:
• WordPress Theme:
• Yoast SEO version: 23.5
• Gutenberg plugin version:
• Elementor plugin version:
• Classic Editor plugin version:
• Relevant plugins in case of a bug: