set default for merge (#1044)

src/axolotl/cli/merge_lora.py

@@ -25,9 +25,16 @@ def do_cli(config: Path = Path("examples/"), **kwargs):
         load_in_8bit=False,
         load_in_4bit=False,
         flash_attention=False,
-        **kwargs
+        **kwargs,
     )
 
+    if not parsed_cfg.lora_model_dir and parsed_cfg.output_dir:
+        parsed_cfg.lora_model_dir = parsed_cfg.output_dir
+    if not Path(parsed_cfg.lora_model_dir).exists():
+        raise ValueError(
+            f"Target directory for merge: `{parsed_cfg.lora_model_dir}` does not exist."
+        )
+
     do_merge_lora(cfg=parsed_cfg, cli_args=parsed_cli_args)