fix: abort training pipeline on dataset conversion failure

studio/backend/core/training/trainer.py

@@ -468,6 +468,14 @@ class UnslothTrainer:
                 print("Stopped during dataset formatting\n")
                 return None
 
+            # Abort if dataset formatting/conversion failed
+            if not dataset_info.get("success", True):
+                errors = dataset_info.get("errors", [])
+                error_msg = "; ".join(errors) if errors else "Dataset formatting failed"
+                logger.error(f"Dataset conversion failed: {error_msg}")
+                self._update_progress(error=error_msg)
+                return None
+
             self._update_progress(status_message=f"Dataset formatted and ready for training")
             print(f"Dataset formatted successfully\n")