[scripts.pixi] Improve error message when out of project directory

src/idiap_devtools/scripts/pixi.py

@@ -122,6 +122,10 @@ def pixi(
         import tomli
 
         pyproject = tomli.load(pyproject.open("rb"))
+    else:
+        raise click.ClickException(
+            f"Cannot find `pyproject.toml` at directory `{str(project_dir)}`"
+        )
 
     # build output TOML pixi file
     config = {}