Try to fix an uninitialised variable for upload

extension/Source/core/Save.php

@@ -347,7 +347,7 @@ class Save {
 
         $sip = new Sip(false);
         $newValues = array();
-        $vars=array();
+        $vars = array();
 
         $formValues = $this->store->getStore(STORE_FORM);
         $primaryRecord = $this->store->getStore(STORE_RECORD); // necessary to check if the current formElement exist as a column of the primary table.
@@ -369,20 +369,20 @@ class Save {
             }
 
             $column = $formElement[FE_NAME];
-            $pathFileName = $this->doUpload($formElement, $formValues[$column], $sip, $modeUpload);
+            $pathFileName = $this->doUpload($formElement, ($formValues[$column]??''), $sip, $modeUpload);
 
-            if($modeUpload==UPLOAD_MODE_DELETEOLD && $pathFileName==''){
-                $pathFileNameTmp='';  // see '4'
+            if ($modeUpload == UPLOAD_MODE_DELETEOLD && $pathFileName == '') {
+                $pathFileNameTmp = '';  // see '4'
             } else {
                 if (empty($pathFileName)) {
-                    $pathFileNameTmp = $primaryRecord[$column]??''; // see '3'. Attention: in case of Advanced Upload, $primaryRecord[$column] does not exist.
+                    $pathFileNameTmp = $primaryRecord[$column] ?? ''; // see '3'. Attention: in case of Advanced Upload, $primaryRecord[$column] does not exist.
                 } else {
                     $pathFileNameTmp = $pathFileName; // see '1,2,5'
                 }
             }
 
             // Get latest file information
-            if($pathFileNameTmp=='') {
+            if ($pathFileNameTmp == '') {
                 // No new upload and no existing: take care to remove previous upload file statistics.
                 $this->store->unsetVar(VAR_FILE_MIME_TYPE, STORE_VAR);
                 $this->store->unsetVar(VAR_FILE_SIZE, STORE_VAR);