storybook: Angular regression `Error trying to diff '[...]' Only arrays and iterables are allowed` when using array properties

Describe the bug Somewhere after 6.4.0-alpha.33 my stories which have an array property with a initial value started to break.

@Component({
  selector: 'app-toolbar',
  template: `<div
      class="texteditor-toolbar"
      role="toolbar"
      aria-orientation="horizontal"
    >
      <ng-container *ngFor="let tool of toolbar; let i = index">
        <button
          class="texteditor-toolbar-action"
          [title]="tool.title"
          tabindex="-1"
        >
          {{ tool.icon }}
        </button>
      </ng-container>
    </div>`,
})
export default class ToolbarComponent {
  public toolbar: ToolConfig[] = [
    {
      action: 'heading',
      options: { level: 1 },
      icon: 'heading1',
      title: 'Heading 1',
    },
    {
      action: 'heading',
      options: { level: 2 },
      icon: 'heading2',
      title: 'Heading 2',
    },
  ];
}

This code results in the following error in the console:

Error trying to diff '[
    {
      action: 'heading',
      options: { level: 1 },
      icon: 'heading1',
      title: 'Heading 1',
    },
    {
      action: 'heading',
      options: { level: 2 },
      icon: 'heading2',
      title: 'Heading 2',
    },
  ]'. Only arrays and iterables are allowed

This appears to happen because storybook tries to set the value of the array it extracted from compodoc as a string. When I add /** @ignore */ to this property it doesn’t happen anymore, because the property is excluded from the documentation. But this isn’t really desirable.

To Reproduce https://github.com/stefan-schweiger/sb-angular-iterator-bug

System

System:
  OS: Windows 10 10.0.19043
  CPU: (12) x64 Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz
Binaries:
  Node: 14.17.6 - C:\Program Files\nodejs\node.EXE       
  Yarn: 1.22.10 - ~\AppData\Roaming\npm\yarn.CMD
  npm: 6.14.15 - C:\Program Files\nodejs\npm.CMD
Browsers:
  Edge: Spartan (44.19041.1023.0), Chromium (93.0.961.52)
npmPackages:
  @storybook/addon-actions: ^6.4.0-alpha.39 => 6.4.0-alpha.39
  @storybook/addon-essentials: ^6.4.0-alpha.39 => 6.4.0-alpha.39
  @storybook/addon-links: ^6.4.0-alpha.39 => 6.4.0-alpha.39
  @storybook/angular: ^6.4.0-alpha.39 => 6.4.0-alpha.39
  @storybook/builder-webpack5: ^6.4.0-alpha.39 => 6.4.0-alpha.39
  @storybook/manager-webpack5: ^6.4.0-alpha.39 => 6.4.0-alpha.39