Error message in debug tutorial is not shown

[byorgey]

Describe the bug
In the "Debug" tutorial you are instructed to crash a robot deliberately. When you do, no error message is displayed.

To Reproduce

• swarm -i Tutorials/crash
• Now execute r <- build {turn right; move; move; move; move}; view r

Expected behavior
A bunch of log messages are shown, but the error message should be shown as well.

Screenshots

Additional context

This issue was first reported by ChucklesTheBeard on Discord.

An error message is generated saying "There's a mountain in the way", but since the tutorial generates a log message immediately after that, the error message is suppressed due to #1877. Some ideas discussed on Discord:

• The simple solution might be to hide only error messages that are more than n seconds old, for some suitable n
• A more complex solution might be to mark messages as "read" or "unread" based on whether they have been displayed in some kind of dialog, and only hide read things