Warning: file_get_contents(libraries/json2/json2.js):…

Warning: file_get_contents(libraries/json2/json2.js): failed to open stream: No such file or directory in Drupal\Core\Asset\JsOptimizer->optimize() (line 25 of /core/lib/Drupal/Core/Asset/JsOptimizer.php) #0 /core/includes/bootstrap.inc(584): _drupal_error_handler_real(2, 'file_get_conten...', '...', 25, Array) #1 [internal function]: _drupal_error_handler(2, 'file_get_conten...', '...', 25, Array) #2 /core/lib/Drupal/Core/Asset/JsOptimizer.php(25): file_get_contents('libraries/json2...') #3

The only module that wants to use the json2 library is the view-slideshow. But within its configuration it states: "To use the advanced options you need to download json2.js. You can do this by clicking the download button at https://github.com/douglascrockford/JSON-js and extract json2.js to libraries/json2"

Why is there are warning in the logs that the json2 library is not yet installed if it is only needed for the advanced options?