Carefully

carefully word-or-list-to-run1 word-or-list-to-run2

Runs the first list of instructions. If the first list contains an error, carefully runs the second list of instructions and sets errormessage to the error that occurred. If there is no error in the first list, the second list is ignored. Since errors caught by carefully will not be accessible by the Help menu item, Last Message, use this command with caution.

Example:

carefully [fd 50]

[announce [No turtle!]]

If you try this with a turtle on the page, it will go forward. If you try it without a turtle on the page, the message will be displayed in an alert box.