📝 Provide detailed reproduction steps (if any)

1. Add a button to the manual test after an editor with the following handler attached:

document.querySelector( '#save' ).addEventListener( 'click', e => {
	e.preventDefault();

	editor.enableReadOnlyMode( 'saving' );
	editor.setData( '' );

	window.document.dispatchEvent( new window.Event( 'selectionchange' ) );

	editor.disableReadOnlyMode( 'saving' );
	editor.focus();
} );

3. In the editor select an image
4. Click created button

✔️ Expected result

Editor content is cleared and editor does not crash.

❌ Actual result

Editor crashes with the _handleSelectionChange in the stack trace.

❓ Possible solution

While debugging I noticed that the fake selection container <-> view selection map is not verified if the selection is still valid and tries to convert an invalid cached selection to model:

📃 Other details

• Browser: …
• OS: …
• First affected CKEditor version: …
• Installed CKEditor plugins: …

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