Fix source language filter

In case the saved "selected languages" contained languages that did not have any installed source, they caused TypeErrors when trying to access them in e.g. "sourcesByLanguage".

src/features/source/components/SourceLanguageSelect.tsx

@@ -68,37 +68,38 @@ export const SourceLanguageSelect = ({
     const languagesSortedBySelectState = useMemo(
         () =>
             toUniqueLanguageCodes([
-                ...tmpSelectedLanguages.toSorted(languageSortComparator),
+                ...tmpSelectedLanguages
+                    .filter((language) => languages.includes(language))
+                    .toSorted(languageSortComparator),
                 ...languages.toSorted(languageSortComparator),
             ]),
         [languages, tmpSelectedLanguages],
     );
 
     const flattenedSourcesByLanguages = useMemo(
-        () => Object.values(languagesSortedBySelectState.map((language) => sourcesByLanguage[language])).flat(),
+        () => languagesSortedBySelectState.map((language) => sourcesByLanguage[language] ?? []).flat(),
         [languagesSortedBySelectState, sourcesByLanguage],
     );
 
     const groupCounts = useMemo(
         () =>
             languagesSortedBySelectState.map((language) => {
-                const isEnabled = tmpSelectedLanguages.includes(language);
+                const isEnabled = tmpSelectedLanguages
+                    .filter((selectedLanguage) => languages.includes(selectedLanguage))
+                    .includes(language);
                 if (!isEnabled) {
                     return 0;
                 }
 
-                return sourcesByLanguage[language]?.length ?? 0;
+                return sourcesByLanguage[language].length;
             }),
-        [sourcesByLanguage, languagesSortedBySelectState],
+        [sourcesByLanguage, languagesSortedBySelectState, languages],
     );
 
     const computeItemKey = VirtuosoUtil.useCreateGroupedComputeItemKey(
         groupCounts,
         useCallback((index) => languagesSortedBySelectState[index], [languagesSortedBySelectState]),
-        useCallback(
-            (index) => flattenedSourcesByLanguages[index].id,
-            [sourcesByLanguage, languagesSortedBySelectState],
-        ),
+        useCallback((index) => flattenedSourcesByLanguages[index].id, [flattenedSourcesByLanguages]),
     );
 
     const handleCancel = () => {