Snippet preview and analysis results broken in PHP 7.0

[tieupmedia]

• I've read and understood the contribution guidelines.
• I've searched for any related issues and avoided creating a duplicate issue.

Please give us a description of what happened.

In the BE analysis and snippet preview aren't working.

In the browser console, a failed xhr request returning an TYPO3 error messsage is seen:

Oops, an error occured!
syntax error, unexpected '?'

Please describe what you expected to happen and why.

Showing the snippet preview and analysis result as intended in the page module in current page overview / current page settings for yoast.

How can we reproduce this behavior?

1. Run TYPO3 8.7.x with PHP 7.0.x
2. Install yoast_seo 5.0.1

How can we resolve this behavior?

In Classes/UserFunctions/SnippetPreview.php the line 118 defines a nullable return value for the function getContentFromUrl().

Remove the nullable declaration or limit the extension to PHP >= 7.1, cause this feature was initial available in PHP 7.1. See https://www.php.net/manual/de/migration71.new-features.php

Btw., please general add the php dependency to ext_emconf.php, correlating to determination in composer.json.

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Additional context

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Technical info

• TYPO3 version: 8.7.24
• Yoast SEO version: 5.0.1
• Relevant extensions in case of a bug:
• PHP-Version: 7.0.x < 7.1

[haassie]

Please be aware that PHP 7.0 is end-of-life. I would really suggest to update your PHP to 7.1+. Will have a look at the patch and we will update version constraints in ext_emconf.php