Add a chapter about errors

One concept that I still find quite hard to grasp are Nushell's errors.
As far as I can tell, they behave like raised exceptions in a language like Python.
They bubble up, but can be caught with try or do -i.
However, I haven't seen that spelled out yet.

I see that nushell errors are also created if external commands exit with a non-zero exit code.
But also that isn't mentioned in the book.

I would be happy to add a chapter about errors in Nushell if someone could me guide through the things I am unsure about.

Topics to cover:

• behavior of errors
• try
• do
• error make
• complete

Nell'issue non sono indicati file, test o punti di ingresso. Inizia esaminando la documentazione di Nushell relativa agli errori, try, do -i, error make e complete, quindi conferma come si comportano i codici di uscita esterni diversi da zero; il lavoro è completato quando viene aggiunto un capitolo che spiega chiaramente ciascun argomento elencato.