[4] install language - an error message when no xml is returned

[alikon]

Pull Request for Issue #38110 .

Summary of Changes

added a check if the xml is returned

Testing Instructions

add a $response->body= ""; on line 153 to simulate the case

Actual result BEFORE applying this Pull Request

PHP Warning: Attempt to read property "extension" on bool in /shared/httpd/dev4/joomla-cms/administrator/components/com_installer/src/Model/LanguagesModel.php on line 158

Expected result AFTER applying this Pull Request

a proper error message

[brianteeman]

I have tested this item ✅ successfully on 6d0afcf

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[Quy]

I have tested this item ✅ successfully on 6d0afcf

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/38113.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/38113.}

[wilsonge]

Thanks!