[Intl] Fix compile type errors

src/Symfony/Component/Intl/Data/Generator/FallbackTrait.php

@@ -25,23 +25,14 @@ trait FallbackTrait
     private $generatingFallback = false;
 
     /**
-     * @param string $tempDir
-     * @param string $displayLocale
-     *
-     * @return array|null
-     *
      * @see AbstractDataGenerator::generateDataForLocale()
      */
-    abstract protected function generateDataForLocale(BundleEntryReaderInterface $reader, $tempDir, $displayLocale);
+    abstract protected function generateDataForLocale(BundleEntryReaderInterface $reader, string $tempDir, string $displayLocale): ?array;
 
     /**
-     * @param string $tempDir
-     *
-     * @return array|null
-     *
      * @see AbstractDataGenerator::generateDataForRoot()
      */
-    abstract protected function generateDataForRoot(BundleEntryReaderInterface $reader, $tempDir);
+    abstract protected function generateDataForRoot(BundleEntryReaderInterface $reader, string $tempDir): ?array;
 
     private function generateFallbackData(BundleEntryReaderInterface $reader, string $tempDir, string $displayLocale): array
     {

src/Symfony/Component/Intl/Data/Generator/LanguageDataGenerator.php

@@ -150,6 +150,7 @@ class LanguageDataGenerator extends AbstractDataGenerator
      */
     protected function generateDataForRoot(BundleEntryReaderInterface $reader, string $tempDir): ?array
     {
+        return null;
     }
 
     /**

src/Symfony/Component/Intl/Data/Generator/LocaleDataGenerator.php

@@ -135,6 +135,7 @@ class LocaleDataGenerator extends AbstractDataGenerator
      */
     protected function generateDataForRoot(BundleEntryReaderInterface $reader, string $tempDir): ?array
     {
+        return null;
     }
 
     /**

src/Symfony/Component/Intl/Data/Generator/RegionDataGenerator.php

@@ -133,6 +133,7 @@ class RegionDataGenerator extends AbstractDataGenerator
      */
     protected function generateDataForRoot(BundleEntryReaderInterface $reader, string $tempDir): ?array
     {
+        return null;
     }
 
     /**

src/Symfony/Component/Intl/Data/Generator/ScriptDataGenerator.php

@@ -86,6 +86,7 @@ class ScriptDataGenerator extends AbstractDataGenerator
      */
     protected function generateDataForRoot(BundleEntryReaderInterface $reader, string $tempDir): ?array
     {
+        return null;
     }
 
     /**