Crash: Reader Detail contentForDisplay() is nil while being rendered

[sentry-io]

Sentry Issue: JETPACK-IOS-159H

EXC_BREAKPOINT: Exception 6, Code 1, Subcode 4310203832
  File "<compiler-generated>", in value
  File "ReaderDetailViewController.swift", line 291, in ReaderDetailViewController.render
  File "ReaderDetailCoordinator.swift", line 319, in ReaderDetailCoordinator.storeAuthenticationCookies
  ?, in RequestAuthenticator.requestForSelfHosted
  File "AuthenticationService.swift", line 93, in AuthenticationService.loadAuthCookiesForWPCom
...
(19 additional frame(s) were not displayed)

[dangermattic]

Thanks for reporting! 👍

[dvdchr]

This issue occurred 5 times, affecting 5 different users in v24.7. Here's where the exception was thrown from:

WordPress-iOS/WordPress/Classes/ViewRelated/Reader/Detail/ReaderDetailViewController.swift

Lines 290 to 292 in b3f0327

	coordinator?.storeAuthenticationCookies(in: webView) { [weak self] in
	self?.webView.loadHTMLString(post.contentForDisplay())
	}

The crash happened because the post's contentForDisplay() unexpectedly returned nil. I suspect this involves state restoration, where the detail screen tried to render a post, but the managed object is not "hydrated" yet. See #23039 for a similar case.

We could silence this issue by ensuring that contentForDisplay() exists, or the more proper solution is to wait (and maybe show a loading state) until the object's properties are populated properly. I'm assigning this to myself for now since this is Reader-related.