Failure to load source node from imported copy produces blank screen

[bjester]

Observed behavior

When clicking the 'Imported from' link on content that was copied / imported into a channel, and the source doesn't exist leading to the following error, the user observes a blank screen.

Expected behavior

Studio should fail gracefully and not present the user with a blank screen. In this case, I believe showing a snackbar with an error message is appropriate. We need to decide what the message should say

User-facing consequences

The blank screen gives no indication of what went wrong. In this scenario, addressing the blank screen and presenting the user with information gives proper defensive behavior against an edge case like this.

Errors and logs

Steps to reproduce the issue

⚠ do not reproduce in production ⚠

1. Import content from another channel
2. Delete the source content node
3. Click the 'Import from' link on the copy