DASH: bug fix for `None` values in history

diff --git a/python_suite/dashboard/dashboard.py b/python_suite/dashboard/dashboard.py
index 92db225eeba11dd200cbf08263a383f29c1817d1..f7fa0567e7c24ab69218e8236abbfa61f02abe15 100755 (executable)
--- a/python_suite/dashboard/dashboard.py
+++ b/python_suite/dashboard/dashboard.py
@@ -33,7 +33,7 @@ def register_pv_value_in_history(pv_name, ts, value):
     # repeat the previous value just before our new NaN value
     # This is important to extend plot lines until the value gets invalid.
     if len(HISTORY[pv_name]) > 0 and value is None:
-        HISTORY[pv_name].append( [ts-0.1, HISTORY[pv_name][1]] )
+        HISTORY[pv_name].append( [ts-0.1, HISTORY[pv_name][-1][1]] )
     HISTORY[pv_name].append( [ts, value] )
 
 def cb_connection_change(**kwargs):