The Output window and errors

When your code has a problem, the Output window gets red lines. That scary-looking line is actually a gift: it tells you exactly where the problem is and what it is.

#The anatomy of an error

Say you run a script and Output shows this:

Workspace.Script:3: attempt to call a nil value

Read it left to right:

• Workspace.Script — which script has the problem
• :3 — the line number in that script
• attempt to call a nil value — the actual problem, in plain English

You won't understand every error yet. But notice how much information is there.

#Make an error on purpose

Open your script from the last lesson and break it on purpose — change the print to:

print()

Press Play. print() needs something between the parentheses, so Output reports an error about a missing argument.

That's success. You just created your first real error on purpose, on your terms, in a safe empty place. An error doesn't mean you broke your game — it means that one line stopped. Read the message, fix the line, try again.

#The habit that separates developers

When something doesn't work, look at the Output window before you look anywhere else. Not the 3D view, not your script's spelling — Output. The message names the script and the line, so you can go straight there.