Reader: Show error description when failing to load posts

[crazytonyli]

Description

Fixes https://linear.app/a8c/issue/CMM-815

After the fix:

Testing instructions

Find a P2 that you are not a member of. Send a post link in that P2 to your test device. Open the link.

BTW, you don't need AutoProxxy to view posts from the app.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 26.5 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	29900
	Version	PR #25017
	Bundle ID	com.jetpack.alpha
	Commit	55fb233
	Installation URL	3d4c1udnqoh68

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	29900
	Version	PR #25017
	Bundle ID	org.wordpress.alpha
	Commit	55fb233
	Installation URL	3cdc8hdhe3sfg

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[kean]

This looks great, but we might want to add some more details if it's a P2 and a A8C account. I'd add something like: "You need to add yourself as a P2 member to view the posts on this device".

[crazytonyli]

@kean I thought about copying the same text from the web page when you visit a private P2 without AutoProxxy. But I didn't want to complicate things, considering the existing message mentions "private blog".

[kean]

@kean I thought about copying the same text from the web page when you visit a private P2 without AutoProxxy. But I didn't want to complicate things, considering the existing message mentions "private blog".

Sounds good. I think it is good enough, and is similar to how the web handles it.