fix(firewall): check if vm exists with a name for private sg (#1092)

PR Close #989

src/app/security-group/sg-list-item/security-group-list-item.component.ts

@@ -1,26 +1,26 @@
-import {
-  EventEmitter,
-  OnChanges,
-  SimpleChanges
-} from '@angular/core';
-import { getType, SecurityGroup } from '../sg.model';
+import { EventEmitter, OnChanges, SimpleChanges } from '@angular/core';
 import { MatMenuTrigger } from '@angular/material';
+
+import { getType, SecurityGroup } from '../sg.model';
 import { VirtualMachine } from '../../vm';
-import { Dictionary } from '@ngrx/entity/src/models';
 import { SecurityGroupViewMode } from '../sg-view-mode';
+import { NgrxEntities } from '../../shared/interfaces';
 
 export class SecurityGroupListItemComponent implements OnChanges {
   public item: SecurityGroup;
   public searchQuery: () => string;
   public onClick = new EventEmitter();
   public matMenuTrigger: MatMenuTrigger;
   public isSelected: (securityGroup) => boolean;
-  public vmList: Dictionary<VirtualMachine>;
+  public vmList: NgrxEntities<VirtualMachine>;
 
   public query: string;
 
   public get sgVmName() {
-    return this.vmList[this.item.virtualMachineIds[0]].name;
+    const vmId = this.item.virtualMachineIds[0];
+    const vm = this.vmList[vmId];
+
+    return vm ? vm.name : '';
   }
 
   public ngOnChanges(changes: SimpleChanges): void {