Message at start when a folder is missing is clearer.

CHANGELOG.md

@@ -5,6 +5,8 @@
 
 - Add more digits in erf/gaussian fit display.
 
+- Message at start when a folder is missing is clearer.
+
 ## v3.1.2
 - Update LICENCE, CONTRIBUTORS, docs.
 

lib/jupylabbook.py

@@ -89,6 +89,9 @@ def start(paths):
     # Check if the paths are ok, and set them
     expt.check_and_set_paths(paths)
 
+    if not expt.is_paths_ok:
+        raise FileNotFoundError('Missing folder or file.')
+
     # Set params to their default values if the first cell
     # has not been executed before (avoid loosing params when reloading
     # the first cell)
@@ -101,6 +104,3 @@ def start(paths):
 
     if expt.is_paths_ok:
         notebook.create_cell_action_widgets(is_delete_current_cell=False)
-
-    elif not expt.is_paths_ok:
-        raise FileNotFoundError('Missing folder or file.')