Describe the bug

To Reproduce
Steps to reproduce the behavior:

1. Run npm ng:serve:web on current main branch.
2. Go to any repo and set the filter to ensure that there is at least 1 hidden user in the GUI
3. Now try to switch to an invalid repo
4. See error

Expected behavior
No such error should appear.

Screenshots

Additional context
Investigation suggests this bug arises from hidden-groups.component.html

...
  <div class="scrollable-container">
    <div *ngFor="let group of groups">
      <ng-container [ngTemplateOutlet]="getCardTemplate()" [ngTemplateOutletContext]="{ $implicit: group }"></ng-container>
    </div>
...

<!-- Templates -->
<ng-template #defaultCard let-group>
...
</ng-template>

<ng-template #assigneeCard let-assignee>
...
</ng-template>

<ng-template #milestoneCard let-milestone>
...
</ng-template>

  @ViewChild('defaultCard') defaultCardTemplate: TemplateRef<any>;
  @ViewChild('assigneeCard') assigneeCardTemplate: TemplateRef<any>;
  @ViewChild('milestoneCard') milestoneCardTemplate: TemplateRef<any>;
// ...
  getCardTemplate(): TemplateRef<any> {
    switch (this.groupingContextService.currGroupBy) {
      case GroupBy.Assignee:
        return this.assigneeCardTemplate;
      case GroupBy.Milestone:
        return this.milestoneCardTemplate;
      default:
        return this.defaultCardTemplate;
    }
  }

How this appeared is the templates are undefined since the UI have not loaded. This causes getCardTemplate() to be undefined when angular is creating the UI. This becomes defined later on, which is uncaught by Angular's internal check during development leading to this issue.