weird issue involving getInversedLocaleFromMapping

[keithwhyman]

I assume I have done something wrong somewhere but... New Laravel 8 sail install Installed laravel-localization over composer. Created a localesMapping 'localesMapping' => [ 'en-GB' => 'uk', 'de-DE' => 'de' ], Redirect not working, 'en' ok, 'de' is a 404 Routing in web is set up so Route::group( [ 'prefix' => LaravelLocalization::setLocale(), 'middleware' => [ 'localize','localeSessionRedirect', 'localizationRedirect', 'localeViewPath' ] ], function() {

After looking into this I find in vendor/mcamara/laravel-localization/src/Mcamara/LaravelLocalization/LaravelLocalization.php the following. When calling LaravelLocalization::setLocale(), I get from $locale = $this->request->segment(1); "de" as expected but then
$locale = $this->getInversedLocaleFromMapping($locale); "de_DE"

And the next part goes wrrong $this->supportedLocales array:2 [▼ "de" => array:4 [▶] "en" => array:4 [▶] ] where obviously de_DE is not found. If I just comment out getInversedLocaleFromMapping then all works fine. What have I done wrong? thanks