bug: Nav `pop()` does not show correct enteringView within a Modal

[sean-perkins]

Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already report this problem, without success.

Ionic Framework Version

• v4.x
• v5.x
• v6.x
• Nightly

Current Behavior

When using nav.pop() there is a couple of behaviors that are incorrect:

1. The leavingView (the view being removed) is not unmounted/removed from the DOM.
2. The enteringView (the view to display) is not visible. The enteringView is being transitioned under another view in the stack.

Expected Behavior

When calling nav.pop(), Nav should unmount/destroy the view that is being removed (the topmost view). Additionally, the next available view that I was just from, should display as the new topmost view.

Steps to Reproduce

1. Open reproduction
2. Click "Open Modal"
3. Click "Go To Page Two"
4. Click "Go To Page Three"
5. Click "Go Back"
6. Observe: Page One is displayed, expected Page Two to display.
7. Observe: page-one, page-two and page-three are all still in the DOM. Expected only page-one and page-two.
8. Observe: page-one has a higher z-index than page-two. Expected that page-two would have a higher z-index than page-one.

Code Reproduction URL

https://stackblitz.com/edit/r1sn2g?file=index.html

Ionic Info

N/A

Additional Information

No response

[sean-perkins]

Narrowed this problem to only using ion-nav within ion-modal.

When the modal is opened, the disconnectedCallback() is fired multiple times for ion-nav. This results in the internal flag destroyed to get set to true, skipping core behavior for unmounting/cleaning up views.

[ionitron-bot]

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