Fix error on subscribing on attributes, that will be used in labels

@@ -158,6 +158,7 @@ export interface TbFlotCustomLegendSettings {
 export interface TbFlotLabelPatternSettings {
   name: string;
   type: DataKeyType;
+  settings?: any;
 }
 
 export interface TbFlotGraphSettings extends TbFlotBaseSettings, TbFlotThresholdsSettings, TbFlotComparisonSettings, TbFlotCustomLegendSettings {

@@ -42,7 +42,7 @@ import {
   flotSettingsSchema,
   TbFlotAxisOptions,
   TbFlotHoverInfo,
-  TbFlotKeySettings,
+  TbFlotKeySettings, TbFlotLabelPatternSettings,
   TbFlotPlotAxis,
   TbFlotPlotDataSeries,
   TbFlotPlotItem,
@@ -383,6 +383,9 @@ export class TbFlot {
     if (this.settings.customLegendEnabled) {
       this.labelPatternsSourcesData = [];
       const labelPatternsDatasources: Datasource[] = [];
+      this.settings.dataKeysListForLabels.forEach((item) => {
+        item.settings = {};
+      });
       subscription.datasources.forEach((item) => {
         let datasource: Datasource = {
           type: item.type,