Merge branch '4.x' of https://github.com/craftcms/cms into 5.x

# Conflicts:
#	CHANGELOG.md

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Craft now sends `X-Robots-Tag: none` headers for preview requests. ([#15612](https://github.com/craftcms/cms/pull/15612), [#15586](https://github.com/craftcms/cms/issues/15586))
 - Fixed a SQL error that occurred when running the `db/convert-charset` command if there were any custom database views or sequences. ([#15598](https://github.com/craftcms/cms/issues/15598))
 - Fixed a bug where `craft\helpers\Db::supportsTimeZones()` could return `false` on databases that supported time zone conversion. ([#15592](https://github.com/craftcms/cms/issues/15592))
+- Fixed a bug where `null` values within associative arrays were ignored when applying project config data. ([#10512](https://github.com/craftcms/cms/issues/10512))
 - Fixed a bug where tabs within field layout designers weren’t always getting positioned correctly when wrapped. ([#15590](https://github.com/craftcms/cms/issues/15590))
 - Fixed a bug where editable table rows’ action buttons were misaligned for newly-created rows. ([#15602](https://github.com/craftcms/cms/issues/15602))
 - Fixed a bug where relational fields’ element query results weren’t limited to the selected relations if the `id` param was overridden. ([#15570](https://github.com/craftcms/cms/issues/15570))

src/helpers/ProjectConfig.php

@@ -440,7 +440,7 @@ public static function unpackAssociativeArray(array $array, bool $recursive = tr
             $associative = [];
             if (!empty($array[ProjectConfigService::ASSOC_KEY])) {
                 foreach ($array[ProjectConfigService::ASSOC_KEY] as $items) {
-                    if (!isset($items[0], $items[1])) {
+                    if (!array_key_exists(0, $items) || !array_key_exists(1, $items)) {
                         Craft::warning('Skipping incomplete packed associative array data', __METHOD__);
                         continue;
                     }