Keep one chart series defined

enterprise/backend/src/baserow_enterprise/integrations/local_baserow/service_types.py

@@ -175,7 +175,9 @@ class LocalBaserowGroupedAggregateRowsUserServiceType(
                         code="invalid_aggregation_raw_type",
                     )
                 else:
-                    series_agg_used.add(series_aggregation_reference)
+                    # It is still possible to have multiple undefined series
+                    if series_aggregation_reference != "field_None_":
+                        series_agg_used.add(series_aggregation_reference)
 
                 return True
 

enterprise/web-frontend/modules/baserow_enterprise/dashboard/components/data_source/AggregationSeriesForm.vue

@@ -47,7 +47,7 @@
         </Dropdown>
       </FormGroup>
     </FormSection>
-    <FormSection>
+    <FormSection v-if="aggregationSeries.length > 1">
       <ButtonText
         icon="iconoir-bin"
         type="secondary"

enterprise/web-frontend/modules/baserow_enterprise/dashboard/components/data_source/GroupedAggregateRowsDataSourceForm.vue

@@ -314,7 +314,9 @@ export default {
     changeTableId(tableId) {
       this.values.table_id = tableId
       this.values.view_id = null
-      this.values.aggregation_series = []
+      this.values.aggregation_series = [
+        { field_id: null, aggregation_type: '' },
+      ]
       this.values.aggregation_group_bys = []
       this.values.aggregation_sorts = []
       this.v$.values.table_id.$touch()