diff --git a/src/app/components/fixedvar-results/fixedvar-results.component.ts b/src/app/components/fixedvar-results/fixedvar-results.component.ts
index 58a9afd15c54dc5a0e5335e6845a9880a6e26ed6..e92ff147fd84b06a9fa5b6e431697c100697f658 100644
--- a/src/app/components/fixedvar-results/fixedvar-results.component.ts
+++ b/src/app/components/fixedvar-results/fixedvar-results.component.ts
@@ -90,7 +90,10 @@ export class FixedVarResultsComponent extends ResultsComponent implements DoChec
 
     public ngDoCheck() {
         if (this._doUpdate) {
-            this._doUpdate = !this.updateResults();
+            // clodo trick @see nghyd#308
+            setTimeout(() => {
+                this._doUpdate = !this.updateResults();
+            }, 10);
         }
     }
 
diff --git a/src/app/components/jet-trajectory-chart/jet-trajectory-chart.component.ts b/src/app/components/jet-trajectory-chart/jet-trajectory-chart.component.ts
index 7143ca68a4b57df31f4c65ff3777d4102bbb1bfc..933162343b6bc53960a72cfff58cd1e88ce7cf96 100644
--- a/src/app/components/jet-trajectory-chart/jet-trajectory-chart.component.ts
+++ b/src/app/components/jet-trajectory-chart/jet-trajectory-chart.component.ts
@@ -135,7 +135,7 @@ export class JetTrajectoryChartComponent extends ResultsComponent {
         this.forceRebuild(); // used for (de)activating legend in generateScatterChart()
         this._results = r;
 
-        if (this._results) {
+        if (this._results && this._results.result) {
             const nub = this._results.result.sourceNub as Jet;
             const length = nub.variatingLength();
             // extract variable values list for legend