How to make Bonita BPM to show an error?

I have an assignment where before I get a message from a server and tweet it, I have to check if an error occurs. If it does, it says that I have to "show with a human task an error message specifying a number and the error received. After that, the process ends".

In another part of the workflow I do check for errors but I'm not required to show anything, and frankly I do not understand how that would work, I believe my mistake is that I might be thinking too literally or too close to code showing errors and such.

Any help or place to look for information?

The answer to this question will vary depending on the edition of Bonita BPM that you are using.

With Community edition:
Note that error management will impact process design.
You can implement the following scenario:

1. retrieve the error (this can be done by using a custom connector output).
2. store the error details in a process variable.
3. have an exclusive gateway with a condition that branches to an optional human task that shows the error in a form.

With Performance edition:
There is a built in error management feature in Bonita BPM Portal. As an administrator you may review stack traces associated to connector execution failures, edit some settings and replay the connectors. All of this is done without impacting the process design.