[BUGFIX] Prevent type errors in ExportController

In case an export is created based on e.g.
an invalid preset, no PHP TypeError should
occur.

This is now fixed by properly typecasting
the input data.

Additionally, two possible undefined array
key access warnings are fixed.

Resolves: #97403
Releases: main, 11.5
Change-Id: I994391909b44247879099ce92d61911c56ca7e39
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78732
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/impexp/Classes/Controller/ExportController.php

@@ -240,7 +240,7 @@ protected function exportData(array $inData): array
         if (!empty($inData['filetype'])) {
             $this->export->setExportFileType((string)$inData['filetype']);
         }
-        $this->export->setExportFileName($inData['filename'] ?? '');
+        $this->export->setExportFileName((string)($inData['filename'] ?? ''));
 
         // Static tables:
         if (is_array($inData['external_static']['tables'] ?? null)) {

typo3/sysext/impexp/Classes/Import.php

@@ -1049,7 +1049,9 @@ protected function addSingle(array &$importData, string $table, int $uid, $pid):
                         // @see fixUidLocalInSysFileReferenceRecords()
                         // If it's empty or a uid to another record the FileExtensionFilter will throw an exception or
                         // delete the reference record if the file extension of the related record doesn't match.
-                        if (!($table === 'sys_file_reference' && $field === 'uid_local')) {
+                        if (!($table === 'sys_file_reference' && $field === 'uid_local')
+                            && is_array($GLOBALS['TCA'][$table]['columns'][$field]['config'] ?? false)
+                        ) {
                             $importData[$table][$ID][$field] = $this->getReferenceDefaultValue($GLOBALS['TCA'][$table]['columns'][$field]['config']);
                         }
                         break;
@@ -1459,7 +1461,7 @@ protected function processSoftReferences(): void
                 if (isset($GLOBALS['TCA'][$table])) {
                     foreach ($records as $uid => $record) {
                         if (is_array($record['softrefs'] ?? null)) {
-                            $actualUid = BackendUtility::wsMapId($table, $this->importMapId[$table][$uid]);
+                            $actualUid = BackendUtility::wsMapId($table, $this->importMapId[$table][$uid] ?? 0);
                             // First, group soft references by record field ...
                             // (this could probably also have been done with $this->dat['records'] instead of $this->dat['header'])
                             $softrefs = [];