Write Failure.

Theory. setItem can throw — most often QuotaExceededError (storage full), but also when writing is forbidden. If you do not catch it, the script stops; if you catch it and still show "Saved", you lie to the user.

Rule for an honest status: show success ONLY after setItem finished without an error.

try { window.labStorage.setItem("last", value); status.textContent = "saved"; } catch (error) { status.textContent = "save-failed"; }

Order matters: setItem comes FIRST, the text "saved" after it (inside try, not before). On error do not clear the field — the user must not lose what they typed — and do not draw the new record as saved.

In Code Lab the host simulates a full store (the first write, or every write after N successful ones, throws QuotaExceededError).

Common mistake: status = "saved" before setItem; an empty catch; clearing the form before a successful write.