promise/prefer-catch

The second argument of then(a, b) only handles a rejection from before the then(). If a itself throws, b isn't called. A catch() after the then() handles both.

The rule only reports a then() call with two arguments when it's a statement by itself. One that's returned, awaited, assigned, or followed by more of the chain isn't reported.

Configure

Off by default. To turn it on:

[lint.rules]
"promise/prefer-catch" = "error" # or "warn"

Examples

Reported:

loadItems().then(render, showError); // an error in render is not handled

loadItems().then(null, showError);

Not reported:

loadItems().then(render).catch(showError);
loadItems().catch(showError);

function refresh() {
  return loadItems().then(render, showError);
}