refactor(webserver): when appending client side context, unnest to NU… (

#2959)

* refactor(webserver): when appending client side context, unnest to NULL if possible

* [autofix.ci] apply automated fixes

* [autofix.ci] apply automated fixes (attempt 2/3)

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

ee/tabby-webserver/src/service/thread.rs

@@ -157,10 +157,15 @@ impl ThreadService for ThreadServiceImpl {
         message: &CreateMessageInput,
     ) -> Result<()> {
         let thread_id = thread_id.as_rowid()?;
-        let client_code = message
-            .attachments
-            .as_ref()
-            .map(|x| x.code.iter().map(Into::into).collect::<Vec<_>>());
+        let client_code = message.attachments.as_ref().and_then(|x| {
+            let code = x.code.iter().map(Into::into).collect::<Vec<_>>();
+            // If there are no code attachments, return None
+            if code.is_empty() {
+                None
+            } else {
+                Some(code)
+            }
+        });
 
         self.db
             .create_thread_message(