Lesson 6 — Config defaults

|| versus ??

Two ways to give a default:

• a || b uses b if a is falsy — that includes 0, "" and false;
• a ?? b uses b only if a is null or undefined.

So with retries: 0, config.retries || 3 gives 3 (wrong — the user asked for 0), while config.retries ?? 3 gives 0.

Why it matters: a config value of 0 or false is a real choice; ?? respects it.