Errors can be caused by wrong input from the user or they can be produced by the system.
If you enter 4 / 0 in the REPL, you will get a *** Math Error: attempt to divide by zero alert. The Red console does not crash in the case of an error, but a compiled program will.
Now, let's return to our guessing game. What happens if the user enters a string such as "abc" instead of a number? Then the guessing stops right there—the program crashes with the error:
;-- see Chapter04/handling-errors.red: ...