Update testing file mock charts

PiperOrigin-RevId: 906389077

Author: Profiler Team

frontend/app/components/chart/chart.ts

@@ -40,7 +40,9 @@ export class Chart implements OnChanges, OnInit {
     }
 
     if (!this.dataInfo || !this.dataInfo.dataProvider) {
-      this.chart.clearChart();
+      if (this.chart.clearChart) {
+        this.chart.clearChart();
+      }
       return;
     }
 

frontend/app/components/overview_page/step_time_graph/step_time_graph.ts

@@ -66,7 +66,7 @@ export class StepTimeGraph implements AfterViewInit, OnChanges {
     const dataTable =
         new google.visualization.DataTable(this.inputPipelineAnalysis);
     const columnsIds =
-        dataTable.getTableProperty('step_time_graph_column_ids').split(',');
+        dataTable.getTableProperty('step_time_graph_column_ids')?.split(',');
     let colors = this.columnColors;
     this.height = 300;
     this.inputPipelineAnalysis.p = this.inputPipelineAnalysis.p || {};
@@ -77,7 +77,7 @@ export class StepTimeGraph implements AfterViewInit, OnChanges {
 
     let i = 0;
     while (i < dataTable.getNumberOfColumns()) {
-      if (!columnsIds.includes(dataTable.getColumnId(i))) {
+      if (!columnsIds?.includes(dataTable.getColumnId(i))) {
         dataTable.removeColumn(i);
         continue;
       }