Error in Infusions

When copy an infusion to the infusions folder of my PHP-fusion installation, following error occured:

// Multilanguage table
81 $inf_mlt[] = [
82 "title" => $locale['articles']['title'],
83 "rights" => "AR"
84 ];
85
86 // Multilanguage links
87 $enabled_languages = makefilelist(LOCALE, ".|..", TRUE, "folders");
88 if (!empty($enabled_languages)) {
89 foreach ($enabled_languages as $language) {
90 include LOCALE.$language."/setup.php";
Line 90 -- 17 seconds ago
include(../locale/German/setup.php): failed to open stream: No such file or directory

(Example from the Articles, but the same for news, forum etc.)

This error comes for every infusion in the /infusions folder.

The problem comes, because I installed PHP-fusion 9.03.50 with only English language, but the infusion I tried to install comes with other languages (German in this case).

I.m.o the system should NOT scan the folders of the infusions (line 87), but only check the enabled languages in the PHPFusion settings.
In this case it finds an German language file, but this file does not exist for all the other infusions.

Edit:
In the infusion was included a user field, with german language.
This files where placed in mydomain.com/locale/German/user_fields/...
If I remove the "German" folder, the error disappears.
So it seems the system is assuming the complete language must be available if there is a folder with that name. Even if this only contains a language file for a userfield.