fix: Add null checks and error handling in Get-XlsFilesRecursive

SharePointFunctions.ps1

@@ -280,8 +280,24 @@ function Get-XlsFilesRecursive {
     
     $allFiles = @()
     
+    # Check if DriveId or DriveItemId is null or empty
+    if ([string]::IsNullOrEmpty($DriveId)) {
+        $script:txtStatus.Text += "Error: DriveId is null or empty`n"
+        return $allFiles
+    }
+    if ([string]::IsNullOrEmpty($DriveItemId)) {
+        $script:txtStatus.Text += "Error: DriveItemId is null or empty`n"
+        return $allFiles
+    }
+    
     # Get items in the current folder
-    $items = Get-MgDriveItemChild -DriveId $DriveId -DriveItemId $DriveItemId
+    try {
+        $items = Get-MgDriveItemChild -DriveId $DriveId -DriveItemId $DriveItemId -ErrorAction Stop
+    }
+    catch {
+        $script:txtStatus.Text += "Error getting items: $($_.Exception.Message)`n"
+        return $allFiles
+    }
     
     foreach ($item in $items) {
         $script:txtStatus.Text += "Checking item: $($item.Name)`n"