Fix/scatter category intervals (#464)

Author: mpolidori

ckanext/querytool/fanstatic/javascript/dist/modules/viz-preview.js

@@ -211,6 +211,7 @@ def querytool_get_chart_data(context, data_dict):
     sql_without_group = sql_string.split('GROUP BY')[0]
     sql_group = sql_string.split('GROUP BY')[1]
     categories_data = {}
+    #log.error(data_dict)
 
     if chart_filter:
         previous_filters.append(chart_filter)
@@ -242,16 +243,17 @@ def querytool_get_chart_data(context, data_dict):
             x.append(value)
 
             for record in records:
+                #log.error(record)
                 if upper_bounds and lower_bounds and \
                    record.get(upper_bounds.lower()) and \
                    record.get(upper_bounds.lower()):
-                    upper_bound_value = record[upper_bounds.lower()]
+                    upper_bound_value = record.get(upper_bounds.lower())
 
                     categories_data.setdefault(
                         upper_bounds.lower(), {}).setdefault(
                         record[x_axis.lower()], []).append(upper_bound_value)
 
-                    lower_bound_value = record[lower_bounds.lower()]
+                    lower_bound_value = record.get(lower_bounds.lower())
 
                     categories_data.setdefault(
                         lower_bounds.lower(), {}).setdefault(