Update helpers/functional.py

helpers/functional.py

@@ -121,7 +121,10 @@ def map_to_image(map, return_centre=False, return_gridcell=False, return_timesta
         if return_gridcell:
             ret.append(meta_row.grid_cell.item())
         if return_timestamp:
-            ret.append(pretty_date(meta_row.timestamp.item()))
+            try:
+                ret.append(pretty_date(meta_row.timestamp.item()))
+            else:
+                ret.append('Not Available')
             
         return ret
     else: