UI: liquid level widget added additional checkup for datasources

ui-ngx/src/app/modules/home/components/widget/lib/indicator/liquid-level-widget.component.ts

@@ -160,26 +160,30 @@ export class LiquidLevelWidgetComponent implements OnInit {
   }
 
   private getData(): Observable<{ svg: string; volume: number; units: string }> {
-    const entityId: EntityId = {
-      entityType: this.ctx.datasources[0].entityType,
-      id: this.ctx.datasources[0].entityId
-    };
+    if (this.ctx.datasources?.length) {
+      const entityId: EntityId = {
+        entityType: this.ctx.datasources[0].entityType,
+        id: this.ctx.datasources[0].entityId
+      };
+
+      return this.getShape(entityId).pipe(
+        switchMap(shape => {
+          this.shape = shape;
+          this.svgParams = svgMapping.get(shape);
+          if (this.svgParams) {
+            return forkJoin([
+              this.resourcesService.loadJsonResource<string>(this.svgParams.svg),
+              this.getTankersParams(entityId)
+            ]).pipe(
+              map(params => ({svg: params[0], ...params[1]}))
+            );
+          }
+          return of(null);
+        })
+      );
+    }
 
-    return this.getShape(entityId).pipe(
-      switchMap(shape => {
-        this.shape = shape;
-        this.svgParams = svgMapping.get(shape);
-        if (this.svgParams) {
-          return forkJoin([
-            this.resourcesService.loadJsonResource<string>(this.svgParams.svg),
-            this.getTankersParams(entityId)
-          ]).pipe(
-            map(params => ({svg: params[0], ...params[1]}))
-          );
-        }
-        return of(null);
-      })
-    );
+    return of(null);
   }
 
   public onInit() {