fix(lint): implement nullish coalescing operator

libs/ui/src/lib/line-chart/line-chart.component.ts

@@ -175,16 +175,13 @@ export class GfLineChartComponent
 
       if (this.chart) {
         this.chart.data = data;
-
-        if (!this.chart.options.plugins) {
-          this.chart.options.plugins = {};
-        }
-
-        this.chart.options.plugins.tooltip =
-          this.getTooltipPluginConfiguration();
         this.chart.options.animations = this.isAnimated
           ? animations
           : undefined;
+        this.chart.options.plugins ??= {};
+        this.chart.options.plugins.tooltip =
+          this.getTooltipPluginConfiguration();
+
         this.chart.update();
       } else {
         this.chart = new Chart(this.chartCanvas.nativeElement, {

libs/ui/src/lib/portfolio-proportion-chart/portfolio-proportion-chart.component.ts

@@ -343,13 +343,10 @@ export class GfPortfolioProportionChartComponent
     if (this.chartCanvas) {
       if (this.chart) {
         this.chart.data = data;
-
+        this.chart.options.plugins ??= {};
-        if (!this.chart.options.plugins) {
-          this.chart.options.plugins = {};
-        }
-
         this.chart.options.plugins.tooltip =
           this.getTooltipPluginConfiguration(data);
+
         this.chart.update();
       } else {
         this.chart = new Chart<'doughnut'>(this.chartCanvas.nativeElement, {

libs/ui/src/lib/treemap-chart/treemap-chart.component.ts

@@ -298,13 +298,10 @@ export class GfTreemapChartComponent
     if (this.chartCanvas) {
       if (this.chart) {
         this.chart.data = data;
-
+        this.chart.options.plugins ??= {};
-        if (!this.chart.options.plugins) {
-          this.chart.options.plugins = {};
-        }
-
         this.chart.options.plugins.tooltip =
           this.getTooltipPluginConfiguration();
+
         this.chart.update();
       } else {
         this.chart = new Chart<'treemap'>(this.chartCanvas.nativeElement, {