Steps to reproduce the issue

• In a component code do call \Joomla\Filter\OutputFilter::stringUrlSafe($someText)

Expected result

• Get the url safe version of text passed to the function.

Actual result

• The response to the call is a Class 'Joomla\Language\Language' not found error

System information (as much as possible)

• Joomla! 3.8.12 Stable [ Amani ] 28-August-2018 14:00 GMT
• English, Catalan and Spanish languages installed
• Multilanguage content disabled (not working on multilanguage yet)
• PHP 7.1.20
• Ubuntu Trusty 64 in a Vagrant box over Virtual Box. BTW, the folder where the site live is shared with a Windows 10 system.

Additional comments

The Language class is defined in the namespace \Joomla\CMS\Language instead of \Joomla\Language\Language as it is written in the OutputFilter class. However, changing the use of line 11 in this class into Joola\CMS\Language\Language raises the runtime error Too few arguments to function Joomla\CMS\Language\Language::getInstance(), 0 passed in /var/www/html/libraries/vendor/joomla/filter/src/OutputFilter.php on line 100 and at least 1 expected